User:Emijrp/All Human Knowledge

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  The Great Library of Alexandria in Egypt
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  Natural History by Pliny the Elder
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  Etymologiae by Isidore of Seville
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  Speculum Maius by Vincent of Beauvais
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  Denis Diderot contributor to Encyclopédie
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  Advertisement for the Encyclopædia Britannica 11th edition
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  Internet Archive PetaBox, designed to store one petabyte (a million gigabytes) of information

Preserving all human knowledge for posterity. It is all-important.

Wikimedia servers, holding terabytes of text and images.

This page, a catalogue of catalogues of all human knowledge, is only 132,689 bytes in size. It can be stored on a 5¼-inch floppy disk.

The Voyager Golden Record are vinyl records (listen in YouTube) which were included aboard both Voyager spacecraft launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them.

Imagine a universe in which every planet shares in the sum of all knowledge.

Knowledge as a social good and the Library of Babel in Wikimanía 2009. (Watch in YouTube)

The idea of compiling all human knowledge in a single work, though not in a single place, is highly seductive. In this essay, we attempt to study how many articles are needed to cover the sum of all human knowledge. As of December 2024, English Wikipedia has 6,918,061 articles and Wikidata includes 114,619,496 items. But both projects are far from being complete.

Of course, there are already articles for all the countries in the world and most of their administrative divisions, millions of biographies, hundreds of thousands of geographical features, tens of thousands of creative works like books and movies, but examining these topics and others with an exhaustive focus still shows millions of missing articles.

"This is a work that cannot be completed except by a society of men of letters and skilled workmen, each working separately on his own part, but all bound together solely by their zeal for the best interests of the human race and a feeling of mutual good will." –Denis Diderot, Encyclopédie (1751–1766)

Wikipedia, Wikidata and their sister projects like Wikimedia Commons have different standards of notability. There have been hot debates about notability, specially in Wikipedia, and despite notability threshold has decreased along the years, it is still stronger in Wikipedia than in Wikidata.

In this essay, it is assumed that any topic described in a reputable source deserves a place in the Wikimedia projects, regardless it is a prominent ancient Greek philosopher or an apparently irrelevant star in a distant galaxy million light-years away. Having that in mind, this page still in expansion, estimates the potential number of items for Wikidata on 2,984,571,655.

In a more exhaustive approach, where even entities known to exist but not described yet are counted, the estimate is increased by several orders of magnitude. Finally, if notability is removed, then the theoretical number of items is $\infty$ infinite.

As of 2024, Wikipedia and its sister projects are backed up in mirrors around the world (hot storage), in the Internet Archive (warm storage) and the Arctic World Archive (cold storage). Though more backups are always desired, specially a full offsite mirror of Wikimedia Commons (over 500 TB) is yet to be done.

You are welcome to improve this page, be bold!

Background

Many individuals devoted their lives to different efforts of knowledge compilation and preservation. Some inspiring cases are Vivian Maier, a nanny that took 150,000 photographs during her lifetime primarily of people and architecture; Paul Mawhinney, who archived a copy of every sold album growing a 3 million vinyl collection; Henry Spencer, a computer scientist that preserved over 2 million Usenet messages onto magnetic tapes or Marion Stokes, who recorded hundreds of thousands of hours of television news footage spanning 35 years.

"Like all persons of the Library, I have traveled in my youth; I have wandered in search of a book, perhaps the catalogue of catalogues..." –Jorge Luis Borges, The Library of Babel (1941)

Before Wikipedia, there were many attemps to compile all human knowledge in a single work. Some examples sorted by date include:

• Library of Alexandria (3rd century BC) in Egypt
• Natural History (AD 77–79) by Pliny the Elder
• Etymologiae (7th century) by Isidore of Seville
• De universo (9th century) by Rabanus Maurus
• Speculum Maius (13th century) by Vincent of Beauvais
• Yongle Encyclopedia (1403–1408) by Ming dynasty
• Bibliotheca universalis (1545–1549) by Conrad Gessner
• The abstracting and indexing project (17th century) by Gottfried Wilhelm Leibniz
• Encyclopédie (1751–1772) by Denis Diderot and Jean le Rond d'Alembert
• Mundaneum (1910) by Paul Otlet and Henri La Fontaine
• Encyclopædia Britannica 11th edition
• And more recently Interpedia (1993) by Rick Gates, Internet Archive (1996) by Brewster Kahle and Wikidata (2012)

Also, hypothetical cases exist: Encyclopedia Galactica (1980) by Carl Sagan in Cosmos, Permanent World Encyclopaedia (1936–1938) by H. G. Wells and Memex (1945) by Vannevar Bush. Finally, there are imaginary examples too: "The Universal Library" (1901) by Kurd Lasswitz, "The Total Library" essay and The Library of Babel (1941) by Jorge Luis Borges, Encyclopedia Galactica (1942) in Foundation series by Isaac Asimov and the Akashic records.

Furthermore, there are thousands of archive, library and museum all over the world preserving human knowledge in several formats: book, manuscript, academic journal, newspaper, magazine, sound and music recording, video recording, play-scripts, patent, database, map, postage stamp, print, drawing and more. Some of the largest ones are: British Library (170 million items), Library of Congress (155 million items), Russian State Library (43 million items), National Diet Library (35 million items), National Library of China (31 million items) and Bibliothèque nationale de France (31 million items).

"There is no practical obstacle whatever now to the creation of an efficient index to all human knowledge, ideas and achievements, to the creation, that is, of a complete planetary memory for all mankind." –H. G. Wells, World Brain (1937)

For completeness of sister projects, see § Sister projects. For an estimate about lost knowledge, see § Destroyed knowledge and Wikipedia:There is a deadline.

Arts

The arts are composed of many endeavors (or artforms) united by their employment of the creative impulse. (Main articles: outline of the visual arts, element of art and Principles of art)

Architecture

architecture is both the process and product of planning, designing and construction. Architectural works, in the material form of buildings, are often perceived as cultural and political symbols and as works of art. Historical civilizations are often identified with their surviving architectural achievements. (Main articles: outline of architecture and lists of buildings and structures) (Main categories: Category:Architecture lists and Category:Lists of buildings and structures) (For libraries, museums, archives, see #GLAM) (For transport infrastructure, see #Transport) (Note: some of these items may overlap)

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
public aquarium (Q2281788): facility with large tanks for water-dwelling species	247	374	533	200	According to Vancouver Aquarium there are 200+ aquaria worldwide.
aqueduct (Q474): structure constructed to convey water	220	611	1,479	1,479	Total number of aqueducts is unknown.
bridge (Q12280): structure that spans and provides a passage over a road, railway, river, or some other obstacle	8,993	29,762	65,623	5,000,000	Total number of bridges is unknown. There are at least 614,000 bridges in the United States,, 39,500 bridges on federal roads in Germany and 17,500 road bridges in the Czechia alone. That gives roughly estimate of 500—2,000 inhabitants per bridge, so the total number would be between 5 and 15 millions worldwide.
bullring (Q1193438): arena where bullfighting is performed	58	360	849	3,500	According to sources, there are 3,500+ bullrings.
castle (Q23413): type of fortified structure built in Europe, Asia and the Middle East during the Middle Ages by nobility	6,162	15,174	31,062	52,000	According to Microsoft Copilot, there are 52,000 castles.
cemetery (Q39614): place of burial	4,140	23,746	389,867	1,200,000	According to Microsoft Copilot, there are 1,200,000 cemeteries.
dam (Q12323): barrier that impounds water or underground streams	5,345	3,429	80,861	800,000	According to International Rivers, by 1997 there were 800,000 dams worldwide, 40,000 over 15m high. (See also GeoNames database)
fountain (Q483453): piece of architecture that ejects water	473	6,649	29,668	140,000	According to Microsoft Copilot, there are 140,000 fountains.
gate (Q53060): point of entry to a space enclosed by building, wall or fence	553	3,929	12,323	12,323	Total number of gates is unknown.
heritage (Q2434238): property, custom, or other material, immaterial or natural object inherited from previous generations, and conserved for its importance for future generations	25,293	127,024	616,890	616,890	Total number of monuments (heritage) is unknown.
horse racing venue (Q11822917): venue used in horse racing	336	324	864	864	Total number of horse racing venues is unknown.
hospital (Q16917): health care facility	7,283	5,865	39,638	16,500	According to Cybermetrics Lab, there are 16,500 hospitals worldwide. According to Microsoft Copilot, there are 66,000 hospitals.
hotel (Q27686): business enterprise that provides lodging in a single building paid on a short-term basis	5,822	14,740	158,254	180,000	According to sources, there are 180,000-400,000+ hotels worldwide.
house (Q3947): building usually intended for living in	27,997	111,957	491,327	491,327	Total number of notable houses is unknown.
lighthouse (Q39715): structure designed to emit light to aid navigation	2,373	3,951	9,858	24,400	According to Lighthouse Directory there are 24,400+ lighthouses worldwide.
military base (Q245016): facility directly owned and operated by or for the military	4,315	3,024	11,687	11,687	Total number of military bases is unknown.
mine (Q820477): place for the extraction of minerals	2,859	2,987	53,005	53,005	Total number of mines is unknown.
movie theater (Q41253): venue, usually a building, for viewing films	2,237	4,275	57,604	60,000	According to Microsoft Copilot, there are 60,000 movie theaters.
observatory (Q62832): location used for observing terrestrial or celestial events	1,076	851	3,848	3,848	Total number of observatories is unknown.
palace (Q16560): grand residence, especially a royal or episcopal residence	2,354	10,736	20,107	20,107	Total number of palaces is unknown.
park (Q22698): permanently dedicated recreation area, often open to the public and generally characterized by natural, historic, or landscape features	15,884	23,091	116,514	1,000,000	According to Microsoft Copilot, there are 1,000,000 parks.
structure of worship (Q1370598): specially designed structure for use in worshipping	46,510	281,255	581,021	581,021	Total number of places of worship is unknown. A quick estimate is one place of worship per settlement. As of 2011, the Catholic Church had 3,068 churches of cathedral and co-cathedral status around the world. Estimations of churches worldwide range from 250,000 to 3,700,000, with 450,000 only in USA. There are 2.5 million mosques in the world.
power station (Q159719): facility generating electric power	5,160	3,988	29,240	29,240	Total number of power stations is unknown.
prison (Q40357): place in which people legally are physically confined and usually deprived of a range of personal freedoms	2,976	1,887	10,523	10,000	Total number of prisons is unknown. According to sources, there are 4,575 prisons in the United States and 1,029 in Russia. A rough estimate is 10,000 prisons worldwide.
research station (Q195339): station that is built for the purpose of conducting scientific research	242	174	575	575	Total number of research stations is unknown. (See Antarctic research station)
reservoir (Q131681): artificial lake impounded using a dam or lock to store water	3,102	3,644	28,493	40,000	Total number of reservoirs is unknown.
school (Q3914): institution for the education of students by teachers	49,495	23,793	769,289	5,500,000	According to Microsoft Copilot, there are 5,500,000 schools.
shopping center (Q11315): complex of shops	3,827	4,009	8,784	116,000	According to Microsoft Copilot, there are 116,000 shopping centers.
skyscraper (Q11303): very tall building	3,106	2,981	4,900	94,000	According to SkyscraperPage there are 94,000+ skyscrapers worldwide.
square (Q174782): open public spaces in cities or towns, usually rectilinear, surrounded by buildings, and often located at the junction of two or more thoroughfares	2,134	16,484	24,520	117,000	According to Microsoft Copilot, there are 117,000 squares.
stadium (Q483110): place or venue for (mostly) outdoor sports, concerts, or other events	8,051	5,535	15,203	11,500	According to World Stadiums there are 11,500+ stadiums worldwide. 689 in Africa, 1,200 in Asia, 286 in Central America, 4,268 in Europe, 527 in Middle East, 2,869 in North America, 284 in Oceania and 1,417 in South America.
street (Q79007): public thoroughfare in a built environment	4,918	174,843	719,329	6,000,000	According to Microsoft Copilot, there are 6,000,000 streets.
theatre building (Q24354): building designed for presentation of dramatic performances	4,465	7,039	17,376	17,376	Total number of theatres is unknown.
tower (Q12518): structure with height greater than width	4,945	18,732	50,676	50,676	Total number of towers is unknown.
tunnel (Q44377): underground passageway	1,365	2,944	21,222	50,000	According to es:Anexo:Túneles de España, in Spain there are 400 road tunnels and 1700 railway tunnels. According to Microsoft Copilot, there are 50,000 tunnels.
university (Q3918): academic institution for further education	14,275	3,498	21,135	20,000	According to Webometrics Ranking of World Universities, there are 20,000+ universities worldwide.
watermill (Q185187): structure that uses a water wheel or turbine to drive a mechanical process	214	2,634	6,848	6,848	Total number of watermills is unknown.
weather station (Q190107): set of sensors that record and provide physical measurements and meteorological parameters	42	134	32,318	32,318	Total number of weather stations is unknown.
windmill (Q38720): machine that converts the energy of wind into rotational energy	596	3,040	4,407	4,407	Total number of windmills is unknown.
zoo (Q43501): collection of assorted wild animal species kept for purposes like: study, conservation and, or, commercial exhibition	1,145	1,661	2,350	10,000	According to sources there are 10,000+ zoos worldwide.
list of building types (Q3634365): Wikimedia list article	0	0	0	0	Total number of building types is unknown.
architectural style (Q32880): visual characteristics of a building	827	328	1,499	1,499	Total number of architectural styles is unknown.
architecture award (Q1829324): type of award	60	32	301	301	Total number of architecture awards is unknown.
Total	281,475	951,494	4,541,870	22,380,891

Cinema, television and radio

(This section excludes biographies) (This section excludes archives)

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
film (Q11424): sequence of images that give the impression of movement, stored on film stock	173,617	16,335	398,292	811,306	According to Internet Movie Database, there are 667,381 movies and 143,925 TV movies.
television series episode (Q21191270): single installment of a television series	15,356	86	179,064	7,983,674	According to Internet Movie Database, there are 7,983,674 TV episodes.
television station (Q1616075): organization that transmits content on television	6,305	1,142	9,802	9,802	According to Federal Communications Commission, there are 1,700+ TV stations (and 2,100+ low power) in USA.
television channel (Q2001305): terrestrial frequency or virtual number over which a television station or television network is distributed	3,483	592	6,306	6,306	Total number of TV channels is unknown. According to sources, there are 700+ in India, 7,200 in Europe as of 2009 (UE 27 + Croatia and Turkey). Total number of defunct channels is unknown.
television program (Q15416): segment of audiovisual content intended for broadcast on television	76,401	3,870	199,691	199,691	Total number of TV programs is unknown. Example: list of Spanish television series contains 800+ series and miniseries.
radio station (Q14350): organization for the production and transmission of radio programs	23,564	946	30,232	30,232	According to The World Factbook, there are 44,000 radio stations worldwide and according to Federal Communications Commission 14,000+ are in USA.
television award (Q1407225): award for excellence of television achievements	255	14	507	507	Total number of TV awards is unknown.
Total	298,981	22,985	823,894	9,041,518

Literature

literature is the art of written works. The word literature literally means: "things made from letters". Literature is commonly classified as having two major forms—fiction and non-fiction—and two major techniques—poetry and prose. (This section excludes #Biographies and #Libraries)

• An academic journal is a peer-reviewed periodical in which scholarship relating to a particular academic discipline is published. Estimates suggest that around 50 million journal articles have been published since the first appearance of the Philosophical Transactions in 1665.
• An encyclopedia is a type of reference work, a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge.
• A novel is a long prose narrative that describes fictional characters and events in the form of a sequential story.
• poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning. See also outline of poetry.
• theatre is a collaborative form of fine art that uses live performers to present the experience of a real or imagined event before a live audience in a specific place. See also outline of theatre.

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
academic journal (Q737498): peer-reviewed periodical relating to an academic discipline	5,076	415	36,177	36,177	Total number of academic journals is unknown. See also Journals cited by Wikipedia.
scholarly article (Q13442814): article in an academic publication, usually peer reviewed	0	0	41,476,409	91,000,000	According to sources, over 50 million journal articles have been published since 1665. Number of records in different academic databases: ScienceOpen (91,000,000) Scholia (41,000,000) Internet Archive Scholar (35,000,000) Europe PubMed Central (34,000,000) Inspec (20,000,000) Compendex (10,000,000) PubMed Central (9,700,000) IEEE Xplore (5,500,000) Elsevier BIOBASE (4,100,000) Academic Search (3,000,000) arXiv (2,400,000) SciELO (230,000) See also lists of important publications in science.
thesis (Q1266946): a scholarly work submitted as a requirement to obtain an academic degree; Use Q187685 for PhD thesis	13	18	148,072	148,072	Total number of thesis is unknown.
bibliography (Q1631107): list of books or documents relevant to a particular subject or author	9,238	492	35,308	35,308	Total number of bibliographies is unknown.
comics (Q1004): creative work in which images and text convey information such as narratives	10,392	400	43,643	43,643	Total number of comics is unknown.
dictionary (Q23622): work that provides word information such as spelling, definition, gender, pronunciation, etymology, etc., where the information provided depends on the kind of dictionary	830	549	5,600	38,000	According to sources, there are 38,000 dictionaries.
dictionary entry (Q1580166): part of a dictionary covering a specific word or phrase; the lexicographical information covered depends on the kind of the dictionary; single dictionary entry covers all senses of the word	14	5	166,968	166,968	Total number of dictionary entries is unknown.
encyclopedia (Q5292): type of reference work	523	452	2,332	13,000	According to sources, there are 13,000 encyclopedias. Some of the most complete encyclopedias are Enciclopedia universal ilustrada europeo-americana (800,000 articles), Encyclopædia Britannica (100,000 articles), Encyclopédie (72,000 articles) and Oxford Reference Online (1,400,000 articles). Wikipedia:WikiProject Missing encyclopedic articles Wikipedia:Size comparisons#Comparison of encyclopedias Portal:Reference Works See more encyclopedias in Google Books and Internet Archive. See also list of encyclopedias by language, list of encyclopedias by branch of knowledge and list of online encyclopedias.
encyclopedia article (Q13433827): part of encyclopedia, sometimes considered as reference work by itself	42	37	814,651	814,651	Total number of encyclopedia articles is unknown.
book (Q571): medium for recording information (words or images) typically on bound pages or more abstractly in electronic or audio form	5,238	1,868	74,451	74,451	Total number of books (without counting separated editions) is unknown.
version, edition or translation (Q3331189): specific version of a work, resulting from its edition, adaptation, or translation; set of substantially similar copies of a work	1,400	4,996	581,339	158,464,880	As of 2010, according to Google, there were 129,864,880 books (considering all editions separately). UNESCO estimates that 2.2 million new titles are published every year, so there are roughly 158,464,880 unique books (editions) in the world as of 2023.
codex (Q213924): book with handwritten content	158	198	454	454	Total number of codices is unknown.
incunable (Q216665): book, pamphlet, or broadside that was printed before the year 1501 in Europe	19	49	666	350,000	According to sources, there are 350,000 editions, around 1.5 million surviving copies, located in over 5,000 libraries worldwide. See also Incunabula Short Title Catalogue (29,777) and Universal Short Title Catalogue (350,000).
manuscript (Q87167): document written by hand	3,354	2,169	186,067	186,067	Total number of manuscripts is unknown.
discourse (Q190539): generalization of the notion of a conversation to any form of communication	191	59	3,095	3,095	Total number of speeches is unknown. See also oral literature.
fictional entity (Q14897293): entity that only exists in a work of fiction	25,613	4,732	125,742	125,742	Total number of fictional entities (characters, locations, events) is unknown.
magazine (Q41298): publication that is typically distributed at a regular interval	20,198	3,917	168,591	168,591	Total number of magazines is unknown. According to sources by country: China (9,000)
newspaper (Q11032): scheduled publication containing news of events, articles, features, editorials, and advertising	30,667	6,678	225,498	225,498	Total number of newspapers is unknown. According to sources by country: India (72,000) China (2,000)
poem (Q5185279): work of poetry, often composed of verses	3,548	1,236	124,997	124,997	Total number of poems is unknown.
play (Q25379): theatrical dramatic work intended to be performed by actors (in theatre, radio or recorded for TV)	6,963	2,239	25,551	25,551	Total number of plays is unknown.
literary award (Q378427): award for authors and literary associations	1,484	222	5,711	5,711	Total number of literature awards is unknown.
Total	124,961	30,731	44,251,322	252,050,856

Performing arts

performing arts are a form of art in which artists use their voices and/or their bodies, often in relation to other objects, to convey artistic expression. It is different from visual arts, which is when artists use paint/canvas or various materials to create physical or static art objects. Performing arts include several disciplines, each performed in front of a live audience.

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
musical instrument (Q34379): device created or adapted to make musical sounds	693	1,705	21,328	21,328	Total number of musical instruments is unknown.
album (Q482994): grouping of album releases by an artist usually released at the same time with the same title and tracks but in different formats for consumption (digital, CD, LP)	155,637	186	300,569	1,000,000	Total number of albums is over 1,000,000. The Freedb database holds information for around 1.5 million compact disc (many are duplicates), AllMusic database contains entries for 800,000 unique albums, Discogs database contains over 890,000 master releases (several versions of releases) and nearly 6.5 million unique individual versions of releases, Jamendo project contains over 50,000 free and open albums. Record-Rama collection holds 3 million albums and singles. New albums in USA: 75,000 (2010), 96,100 (2009), 106,000 (2008), 76,000 (2006) See also list of online music databases.
song (Q7366): musical composition for voice(s)	8,893	966	28,743	97,000,000	According to sources, there are 97 million songs.
Total	165,223	2,857	350,640	98,021,328

Visual arts

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
drawing (Q93184): visual artwork in two-dimensional medium	266	625	170,769	170,769	Total number of drawings is unknown.
painting (Q3305213): visual artwork, surface artistically covered with paint	9,511	23,740	973,102	10,000,000	Total number of paintings is unknown. According to Art UK database there are 213,000 artworks contained within the UK's national collection. See also Wikidata:WikiProject sum of all paintings.
photograph (Q125191): image created by light falling on a light-sensitive surface	221	181	80,360	80,360	Total number of photographs is unknown.
sculpture (Q860861): three-dimensional work of art	14,889	129,612	700,011	700,011	Total number of sculptures is unknown.
Total	24,887	154,158	1,924,242	10,951,140

Geography

Human geography

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
sovereign state (Q3624078): state that has the highest authority over a territory	220	200	228	228	193 member states of the United Nations and historical states.
first-level administrative division (Q10864048): administrative division directly subordinate to or under administration of a national government	4,736	898	5,674	5,674	Total number of first-level administrative divisions is unknown.
second-level administrative division (Q13220204): administrative division subordinate to or under administration of a first-level division	60,943	17,889	76,174	76,174	Total number of second-level administrative divisions is unknown.
third-level administrative division (Q13221722): administrative division subordinate to or under administration of a second-level division	75,659	35,157	198,628	198,628	Total number of third-level administrative divisions is unknown.
fourth-level administrative division (Q14757767): administrative division subordinate to or under administration of a third-level division	148,074	39,791	521,841	521,841	Total number of fourth-level administrative divisions is unknown.
fifth-level administrative division (Q15640612): administrative division subordinate to or under administration of a fourth-level division	38,859	1,434	743,442	743,442	Total number of fifth-level administrative divisions is unknown.
sixth-level administrative division (Q22927291): administrative division subordinate to or under administration of a fifth-level division	65	35	32,095	32,095	Total number of sixth-level administrative divisions is unknown.
micronation (Q188443): small, unrecognized country	102	42	151	151	Total number of micronations is unknown.
Total	328,658	95,446	1,578,233	1,578,233

Physical geography

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
continent (Q5107): large landmass identified by convention	48	21	58	58	Current continents and ancient or hypothesized ones.
canal (Q12284): man-made channel for water	1,237	3,021	65,310	65,310	Total number of canals is unknown.
cave (Q35509): natural void under the Earth's surface	1,700	3,422	19,854	2,400	World Caves Database includes 2,424 caves deeper than 300m (total height) or longer than 3km.
desert (Q8514): barren area of land where little precipitation occurs	185	111	2,681	2,681	Total number of deserts is unknown.
oasis (Q43742): isolated area of vegetation in a desert	53	28	185	185	Total number of oases is unknown.
forest (Q4421): dense collection of trees covering a relatively large area	1,599	2,312	28,317	28,317	Total number of forests is unknown.
glacier (Q35666): large persistent body of ice	3,106	973	9,593	100,000	Total number of glaciers is unknown. According to sources by country: Kyrgyzstan (8,000) United States (100,000)
hill (Q54050): landform that extends above the surrounding terrain in lower mountain ranges, smaller than a mountain	3,855	3,349	327,419	327,419	Total number of hills is unknown.
island (Q23442): piece of sub-continental land completely surrounded by water	14,025	7,656	216,648	100,000	Total number of islands is unknown. According to sources are approximately 45,000 tropical islands.
lake (Q23397): body of relatively still water, localized in a basin	16,789	16,884	334,365	1,000,000	Total number of lakes is unknown. According to sources by country: Belarus (11,000) Canada (31,752) Finland (187,888) Norway (450,000) Sweden (150,000)
mountain (Q8502): large natural elevation of the Earth's surface	29,368	22,504	521,756	521,756	Total number of mountains is unknown. Mountains Mount includes info over 100,000 mountains. According to sources by elevation: Above 8,000 m (14) Above 7,000 m (???) Above 6,000 m (???) Above 5,000 m (???)
mountain system (Q46831): geographic area containing several geologically related mountains, group of mountain ranges	4,887	2,304	28,190	28,190	Total number of mountain ranges is unknown.
river (Q4022): larger natural watercourse	40,948	20,621	503,971	1,000,000	Total number of rivers is unknown. According to sources, there are 146,000+ in Africa and 104,000+ in Europe. According to sources by country: Azerbaijan (8,359) Brazil (25,000) China (20,000) El Salvador (300) Georgia (26,000) Guatemala (3,000) Kyrgyzstan (25,000) Nepal (6,000) Panama (500) Romania (4,000) Russia (120,000) Spain (1,800) Ukraine (71,000) United States (250,000) Venezuela (1,000)
sea (Q165): large body of saline water	148	48	239	150	Total number of seas is unknown.
volcano (Q8072): natural, surface vent or fissure usually in a mountainous form	1,118	966	2,830	1,500	According to sources, there are over 1,500 volcanoes worldwide.
Total	119,066	84,220	2,061,416	3,177,966

History

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
calendar day of a given year (Q47150325): specific date (day) of a given year in Gregorian or Julian calendars. See property "point in time" (P585).	5,501	38,507	201,297	201,297	Total number of calendar days is unknown.
event (Q1656682): temporary and scheduled happening, like a conference, festival, competition or similar	440,252	61,713	1,306,283	1,306,283	Total number of events is unknown.
events in a specific year or time period (Q18340514): facts and events ranged in chronological order	26,958	1,233	50,427	200,000	Assuming 200 countries and 1,000 years, there could be 200,000 articles. See also list of time periods, history by period, Category:Year lists and list of calendars.
disaster (Q3839081): hazard resulting in an event causing significant physical damage, destruction or death	11,572	3,484	20,035	20,035	Total number of disasters is unknown.
public election (Q40231): process by which a population chooses the holder of a public office	44,742	3,606	79,706	79,706	Total number of elections is unknown.
time of day (Q1260524): type of occurrence	16	22	87,902	86,400	A day can be divided into 86,400 seconds.
Total	529,041	108,565	1,745,650	1,893,721

GLAM

Glam is an acronym for "galleries, libraries, archives, and museums", although other versions of the acronym exist, such as LAM, which incorporates only libraries, archives, and museums. More generally, GLAMs are publicly funded, publicly accountable institutions collecting cultural heritage materials. (For books and publications, see #Literature)

• An archive is an accumulation of historical records, or the physical place they are located. Archives contain primary source documents that have accumulated over the course of an individual or organization's lifetime, and are kept to show the function of that person or organization.

• A library is an organized collection of information resources made accessible to a defined community for reference or borrowing. It provides physical or digital access to material, and may be a physical building or room, or a virtual space, or both.

• A museum is an institution that cares for (conserves) a collection of artifacts and other objects of scientific, artistic, cultural, or historical importance and makes them available for public viewing through exhibits that may be permanent or temporary.

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
archive (Q166118): agency or institution responsible for the preservation and communication of records selected for permanent preservation	1,811	2,176	23,714	23,714	Total number of archives is unknown. According to sources by country: Spain (34,000) United Kingdom (2,389)
library (Q7075): institution charged with the care of a collection of literary, musical, artistic, or reference materials, such as books, manuscripts, recordings, or films	4,333	6,145	104,610	72,000	According to OCLC, there are 72,000+ libraries in 170 countries. According to sources by country: Burundi (60) Canada (4,154) Croatia (232) Cuba (400) Czech Republic (6,245) Denmark (250) Finland (1,471) France (1,620) Germany (6,313) Greece (672) Hungary (3,518) Iceland (187) Latvia (998) Lithuania (1,478) Morocco (18) Netherlands (579) North Korea (200) Norway (1,108) Panama (40) Peru (200) Poland (9,230) Portugal (168) Romania (2,950) Russia (50,032) Sweden (324) Tanzania (16) Tunisia (200) Ukraine (21,857) United Kingdom (5,500) United States (139,000) Zimbabwe (76) According to sources by size: British Library (150,000,000 items) Smithsonian Institution (137,000,000 items) Library of Congress (32,000,000 items) See also list of national and state libraries, list of the largest libraries in the United States, list of libraries in the ancient world, list of destroyed libraries and list of digital library projects.
museum (Q33506): institution that holds artifacts and other objects of scientific, artistic, cultural, historical, or other importance	19,726	32,944	76,726	55,000	According to The World Museum Community, there are 55,000+ museums in 202 countries. About 17,673 museums in Europe, based on 2003 and 2008 figures. According to sources by country: Australia (1,019) Canada (2,400) Finland (280) France (1,000) Germany (4,000) Hungary (500) Iceland (50) Morocco (11) Pakistan (27) Peru (250) Poland (500) Portugal (300) Romania (400) Russia (1,000) Spain (1,400) Sweden (200) United Kingdom (2,500) United States (17,500) According to sources by size: Metropolitan Museum of Art (2,000,000 items) Tokyo National Museum (110,000 items) Louvre Museum (30,000 items) See also list of national museums.
collection (Q2668072): set of purposefully gathered physical or digital objects with some common characteristics	51,003	17,316	829,533	829,533	Total number of collections is unknown.
Total	76,873	58,581	1,034,583	980,247

Science

Astronomy

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
galaxy (Q318): large gravitationally bound system of stars and interstellar matter	2,594	4,570	2,459,306	2,459,306	Total number of galaxies in the observable universe ranges from 2*10^11 to 2*10^12.
star (Q523): astronomical object consisting of a luminous spheroid of plasma held together by its own gravity	5,242	508	4,485,201	1,811,709,771	Total number of stars in the observable universe ranges from 10^22 to 10^24. Only a tiny fraction have been described, about 1,811,709,771 in the Gaia Data Release 3 by the Gaia European space mission.
black hole (Q589): astronomical object so massive, that anything falling into it, including light, cannot escape its gravity	6	4	13	13	Total number of black holes is unknown.
pulsar (Q4360): highly magnetized, rapidly rotating neutron star or white dwarf	67	17	2,805	2,805	Total number of pulsars is unknown.
supernova (Q3937): star exploding at the end of its stellar lifespan	86	42	14,480	14,480	Total number of supernovae is unknown.
exoplanet (Q44559): any planet beyond the Solar System	1,538	263	10,096	10,096	Total number of exoplanets is unknown.
natural satellite (Q2537): celestial body that orbits a planet or other smaller body in turn directly orbiting a star	323	163	450	450	Total number of natural satellites is unknown.
asteroid (Q3863): minor planet of the inner Solar System; not a comet	28,765	2,125	248,768	248,768	Total number of asteroids is unknown.
comet (Q3559): icy small astronomical object	648	142	1,313	1,313	Total number of comets is unknown.
astronomical radio source (Q1931185): object in outer space that emits strong radio waves	362	423	391,408	391,408	Total number of radio sources is unknown.
Total	39,631	8,257	7,613,840	1,814,838,410

Biology

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
domain (Q146481): taxonomic rank (for "ordinary" organisms thus not viruses)	3	2	6	6	According to sources, there are 3 domains.
kingdom (Q36732): taxonomic rank	16	5	40	40	Total number of kingdoms is unknown.
phylum (Q38348): main taxonomic rank (under the rank kingdom)	172	20	324	324	Total number of phyla is unknown.
class (Q37517): taxonomic rank in biology	436	78	1,050	1,050	Total number of classes is unknown.
order (Q36602): taxonomic rank	1,683	356	3,722	3,722	Total number of orders is unknown.
family (Q35409): taxonomic rank (or a taxon at that rank) between order and genus	9,793	1,957	22,043	22,043	Total number of families is unknown.
genus (Q34740): taxonomic rank used in the biological classification of living and fossil organisms, and viruses	102,456	19,744	274,509	274,509	Total number of genera is unknown.
species (Q7432): one of the basic units of biological classification and a taxonomic rank	353,888	233,217	3,200,772	8,000,000	Acording to sources, there are 8 million species. More than 99% of all species, amounting to over 5 billion species, that ever lived on Earth are extinct.
cell line (Q21014462): A population of cells that originates from a primary culture, adapted to grow and divide under laboratory conditions. Used in biotechnology to consistently produce biological substances	94	35	153,646	153,646	Total number of cell lines is unknown.
gene (Q7187): basic physical and functional unit of heredity	12,179	421	1,266,805	1,266,805	Total number of genes is unknown.
protein (Q8054): biomolecule or biomolecule complex largely consisting of chains of amino acid residues	2,032	308	1,020,996	200,000,000	According to sources, there are 200 million known proteins across all life forms.
non-coding RNA (Q427087): class of RNA that is not translated into proteins	282	3	116,029	116,029	Total number of non-coding RNA is unknown.
Total	483,034	256,146	6,059,942	209,838,174

Chemistry and physics

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
chemical compound (Q11173): pure chemical substance consisting of two or more different chemical elements	0	0	1,146,000	60,000,000	According to CAS Registry Number, there are 60 million chemical compounds (with a growth of 10 million in less than two years). See also list of minerals.
Total	0	0	1,146,000	60,000,000

Health

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
clinical trial (Q30612): human subject research in medicine	34	4	391,959	391,959	Total number of clinical trials is unknown.
disease (Q12136): abnormal condition negatively affecting organisms	4,816	1,477	12,630	12,000	According to sources, there are 12,000 diseases. See also Category:Animal diseases and lists of plant diseases.
drug (Q8386): chemical substance having an effect on the body	1,073	192	4,806	21,000	According to sources, there are 21,000 drugs.
Total	5,923	1,673	409,395	424,959

Mathematics

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
number (Q11563): mathematical object used to count, label, and measure	2,609	15,641	302,062	1,000,000	According to mathematics, there are ℵ0 (infinite) numbers, integers and reals. Let's assume 1,000,000 notable numbers.
prime number (Q49008): positive integer with exactly two divisors, 1 and itself	203	1,207	127,551	1,000,000	According to mathematics, there are ℵ0 (infinite) prime numbers. Let's assume 1,000,000 notable prime numbers.
integer sequence (Q2297602): ordered succession of integers, defined by a formula, recurrence, or property of its members	124	14	205	200,000	According to sources, there are over 200,000 integer sequences.
Total	2,936	16,862	429,818	2,200,000

Research

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
research project (Q1298668): project of one or more scientists, or of an organization in a scientific field	1,206	314	482,438	482,438	Total number of research projects is unknown.
Total	1,206	314	482,438	482,438

Society

A society is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations.

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
human (Q5): any member of Homo sapiens, unique extant species of the genus Homo, from embryo to adult	2,466,017	0	11,297,772	108,000,000	Total number of notable biographies is unknown. As of March 2017, Wikidata included 2,653,023 male biographies and 530,490 female biographies. That is a gender ratio of 5:1. As of 2024, English Wikipedia contains 2,466,017 biographies. We could assume that in an average city with a population of 100,000 inhabitants there are 100 notable people: artists, scientists, writers, politicians, sportspeople and many more. If we agree with that, it means a 1 of 1000 notability rate. If the world population is about 8,000,000,000, we have 8,000,000,000/1,000 = 8,000,000 notable biographies of living people (BLP). Or given the fact that there are about 360,000 births per day, around 360 notable people are born each day. But we have to look into the past centuries too. The number of people who have ever been born is around 100,000,000,000. That gives us an estimate of 100,000,000 notable biographies (plus 8,000,000 BLP) in human history, but hardly there is information about that much people who lived in ancient times. Anyway, a rough estimate is over 108,000,000 notable biographies. Lists of people by occupation (cat) and nationality are desirable too. According to Wikidata, there are over 9,115 occupations (over 6,841 with an English label). See also Category:Obsolete occupations.
given name (Q202444): name typically used to differentiate people from the same family, clan, or other social group who have a common last name	12,874	26,249	117,248	117,248	Total number of given names is unknown.
family name (Q101352): part of a naming scheme for individuals, used in many cultures worldwide	68,799	191,858	658,394	658,394	Total number of family names is unknown.
business (Q4830453): organization undertaking commercial, industrial, or professional activity	109,097	76,559	571,452	571,452	Total number of business is unknown.
craft (Q2207288): field of work that requires particular skills and knowledge of skilled work	164	189	1,017	1,017	Total number of crafts is unknown.
organization (Q43229): social entity established to meet needs or pursue goals	no value	no value	3,869,969	200,000,000	Total number of organizations is unknown. According to sources, non-governmental organizations by country: India (3,300,000) Russia (277,000) United States (1,500,000) Assuming ~200 countries and an average of 1,000,000 organizations by country, we have 200,000,000 organizations.
position (Q4164871): social role with a set of powers and responsibilities within an organization	24,384	3,795	204,719	204,719	Total number of positions is unknown.
human language (Q20162172): set of all languages currently or formerly spoken, written, or signed by humans (excluding computer languages and mathematical/logically-formal languages)	7,095	89	8,480	6,900	According to sources, there are over 6,900 languages. Rosetta Project (Q1550475) is a permanent archive of 1,500 languages (13,000 microscopic pages of text) in a contemporary version of the historic Rosetta Stone (Q48584) to last from 2000 to 12,000 AD. See also list of constructed languages (Q33683), lists of extinct languages (Q175050) and list of constructed languages (Q33683). And wiktionary:Category:All languages for words in all languages.
religion (Q9174): social-cultural system	587	150	995	4,200	According to sources, there are 4,200 religions. pl:Encyklopedia Katolicka has over 40,000 definitions (it includes things like Fire in religion).
Total	2,689,017	298,889	16,730,046	309,563,930

Technology

technology is the making, modification, usage, and knowledge of physical tool, machine, techniques, craft, system, methods of organization, in order to solve a problem, improve a preexisting solution to a problem, achieve a goal or perform a specific function. It can also refer to the collection of such tools, machinery, modifications, arrangements and procedures. Technologies significantly affect human as well as other animal species' ability to control and adapt to their natural environments. See also w:Category:Technology-related lists.

Inventions

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
patent (Q253623): monopoly granted on a new invention	5	44	282,835	140,000,000	Total number of patents is unknown. Patents databases: Espacenet (140,000,000) Japan Patent Office (???) United States Patent and Trademark Office (7,950,000)
Total	5	44	282,835	140,000,000

Software

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
application (Q166142): software program or group of programs designed for end-users	4,262	1,548	9,920	1,000,000	Total number of applications is unknown. According to repositories: App Store (550,000) Google Play (Q79576) (500,000) Ubuntu Software Center (Q70029) (30,000)
malware (Q14001): software that is intentionally hostile, intrusive, or damaging to a computer or network	204	9	302	1,000,000	According to sources, there are over 1,000,000 computer viruses.
Total	4,466	1,557	10,222	2,000,000

Transport

Topic	Enwiki	Commons	Wikidata	Estimate	References	Image
airport (Q1248784): location where aircraft take off and land with extended support facilities, mostly for commercial air transport	12,590	4,145	25,052	43,982	According to sources, there are 43,982 airports.
port (Q44782): maritime facility where ships may dock to load and discharge passengers and cargo	1,433	2,480	7,270	7,270	Total number of ports is unknown.
railway station (Q55488): railway facility where trains regularly stop to load or unload passengers and/or freight	57,364	73,559	152,385	152,385	Total number of train stations is unknown.
road (Q34442): wide way leading from one place to another, especially one with a specially prepared surface which vehicles can use	34,763	215,082	832,389	36,118,087	According to the CIA World Factbook, there are 36,118,087 roads in the world
Total	106,150	295,266	1,017,096	36,321,724

Special pages

Page type	Enwiki	Commons	Wikidata	Estimate	References
Wikimedia category (Q4167836): use with 'instance of' (P31) for Wikimedia category	2,383,569	0	5,671,248	5,671,248	Total number of required categories is unknown. See en:Wikipedia:Database reports/Page count by namespace.
Wikimedia disambiguation page (Q4167410): type of wiki page usually in main namespace (article namespace, ns=0) containing links to articles with similar names, and very little details only, use with P31 "instance of"	400,687	16,291	1,589,814	1,589,814	Total number of required disambiguation pages is unknown.
Wikimedia list article (Q13406463): page of a Wikimedia project with a list of something	235,470	29,028	528,754	528,754	Total number of required lists is unknown.
Wikimedia portal (Q4663903): pages on a Wikimedia wiki intended to serve as "Main Pages" for specific areas of knowledge or information, or for specific audiences and activities. Use with P31 'instance of' for them	783	8	6,051	6,051	Total number of required portals is unknown.
Wikimedia template (Q11266439): type of page in the Wikimedia system. Use with P31 'instance of' for template pages	387,010	5,895	1,030,253	1,030,253	Total number of required template pages is unknown.
Total	3,407,519	51,222	8,826,120	8,826,120

Datasets

Dataset	Enwiki	Commons	Wikidata	Estimate	References
IMDb ID (P345)	no value	no value	no value	30,998,431	As of 2024, this dataset includes 17,855,335 titles and 13,143,096 names.
Freebase ID (P646)	no value	no value	no value	7,451,019	This dataset includes 7,451,019 objects.
SIMBAD ID (P3083)	no value	no value	no value	17,094,596	As of 2024, this dataset includes 17,094,596 objects.
Internet Archive ID (P724)	no value	no value	no value	no value
Open Library ID (P648)	no value	no value	no value	no value
OCLC control number (P243)	no value	no value	no value	no value

Sister projects

Sister project	Content pages	Categories	Files/Images	Estimate	References
Abstract Wikipedia (Q96807071): Wikimedia project using Wikifunctions, Wikidata and various components focusing on extending and complement Wikipedia on all its supported languages (this is not a wiki)	no value	no value	no value	no value	See meta:Abstract Wikipedia.
Wikibooks (Q367): collaborative development of free textbooks	377,711	no value	no value	no value	See meta:Wikibooks.
Wikidata (Q2013): free knowledge graph hosted by Wikimedia and edited by volunteers	110,531,047	no value	no value	2,632,271,006	See meta:Wikidata.
Wikifunctions (Q104587954): Wikimedia project for maintaining an open library of reusable code	8,458	no value	no value	no value	See meta:Wikifunctions.
Wikimedia Commons (Q565): online repository of free-use image, sound, and other media files; part of the Wikimedia ecosystem	no value	no value	106,400,590	2,017,000,000	At least a picture of every notable person (8,000,000). At least a picture, sound recording and video of every species (3x8,000,000=24,000,000). At least ten pictures of every monument (10x590,104=5,901,040). At least a hundred pictures of every populated place (100x1,500,000=150,000,000). A PDF/DJVU file of every book in the public domain (15,846,488). At least a picture of every galaxy (2,459,296) and every star (1,811,709,771). See meta:Wikimedia Commons.
Wikinews (Q964): open-content online news written and edited by volunteers	1,752,046	no value	no value	no value	See meta:Wikinews.
Wikiquote (Q369): open collection of quotes that anyone can edit	325,927	no value	no value	no value	A page of every notable person. See meta:Wikiquote.
Wikisource (Q263): online library that collects open-content source material	6,067,559	no value	no value	1,584,648,800	A page of every book page. Assuming only 10% of 158,464,880 books are in the public domain and every book has 100 pages, it makes 1.5 billion pages. See meta:Wikisource.
Wikispecies (Q13679): open online species directory that anyone can edit	877,864	no value	no value	8,000,000	A page of every species (8,000,000). See meta:Wikispecies.
Wikiversity (Q370): Wikiproject focused on learning, teaching, research, service and ideas materials and activities	149,629	no value	no value	no value	See meta:Wikiversity.
Wikivoyage (Q373): free online travel guide that anyone can edit	135,628	no value	no value	1,500,000	A page of every populated place (1,500,000). See meta:Wikivoyage.
Wiktionary (Q151): free online dictionary that anyone can edit	39,772,549	no value	no value	no value	A page of every word in every language. See meta:Wiktionary.

Non-described entities

In 1584, the Italian philosopher and astronomer Giordano Bruno (Q36330) proposed an unbounded universe in On the Infinite Universe and Worlds: "Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds."

Non-described entities are those known to exist but we don't have direct information about them. Still, they would be notable if we acquire knowledge about them.

For example, total number of galaxies in the observable universe ranges from 200,000,000,000 (2*10^11) to 2,000,000,000,000 (2*10^12) but we don't have data about all of them. The same happens to stars, total number of stars in the observable universe ranges from 10,000,000,000,000,000,000,000 (10^22) to 1,000,000,000,000,000,000,000,000 (10^24). Only a tiny fraction (<0.00000000001%) have been described, about 1,811,709,771 in the Gaia Data Release 3 by the Gaia European space mission.

This is extensible to other astronomical bodies like planets and asteroids, which populate every solar system. According to this approach, the potential number of items for Wikidata is over 1,000,000,000,000,000,000,000,000,000 (10^27).

At this scale, adding any human creation (like books, films, monuments) to the count, is irrelevant to the estimate. Furthermore, this estimate is only about the observable universe. Whether universe is infinite is still an open question of cosmology.

Non-notable entities

There are infinitely many primes.

Non-notable entities are those known to exist but not included in Wikipedia/Wikidata for notability reasons. We can have information about them or not.

After counting galaxies and stars, one could think the next step are sand grains or atoms in the universe (10^80). But there are something better studied and even larger: numbers. Some numbers have their own Wikipedia article, but it isn't common or remotely exhaustive. We could hardly create and store an item for every atom in the universe, though definitely not for every number. But there is a solution, we could generate items for any number and its mathematical properties dynamically.

Despite many numbers can be seen as prosaic, among the most interesting ones are prime numbers. As demonstrated by Euclid (Q8747) around 300 BC, there are infinitely many primes. As of 2018, the largest known prime number is 2^82,589,933 − 1, a Mersenne prime with 24,862,048 decimal digits:

148894445742041325547806458472397916603026273992795324185271289425213239361064475310309971132180337174752834401423587560 ...

(24,861,808 digits skipped)

... 062107557947958297531595208807192693676521782184472526640076912114355308311969487633766457823695074037951210325217902591

According to this approach, the potential number of items for Wikidata is $\infty$ infinite.

Destroyed knowledge

See Wikipedia:There is a deadline

Bibliography

Academia

• Nielsen, Finn (2010). Wikipedia is not the sum of all human knowledge: do we need a wiki for open data?
• Nielsen, Finn et al. (2017). Scholia and scientometrics with Wikidata

Documentaries

• Resnais, Alain (1956). Toute la mémoire du monde.
• Deepspeed media (2013). Internet Archive.
• Haak, Bregtje van der (2014). Digital Amnesia.
• Levie, Françoise (2002). The Man Who Wanted to Classify the World.
• Moledo, Leonardo (2009). El conocimiento como bien social y la Biblioteca de Babel.

Essays

• World Brain: The Idea of a Permanent World Encyclopaedia
• Lasswitz and Borges: Indexing the Library of Everything
• Qu’un milliard d’articles s’épanouissent
• Où s'arrêtera Wikipédia?

News

• Surmounting the Insurmountable: Wikipedia Is Nearing Completion, in a Sense (The Atlantic)
• Wikipedia Is Nearing "Completion" (Slashdot)
• Wikipedia's 5 million articles still cover less than 5 per cent of all human knowledge (Telegraph)

Other

• Ask Slashdot: Permanent Preservation of Human Knowledge?
• Does Wikipedia represent ‘the sum of all human knowledge’? Examining the geographical scope of a peer-produced encyclopedia
• Can we count the sum of all human knowledge?

See also

• Wikipedia:WikiProject Missing encyclopedic articles

External links

• Wikidata project and its query service