Social web

Classification that emerges from many users freely tagging content; the term was coined by Thomas Vander Wal in 2004 and became the bottom-up counterpoint to formal ontologies.

A word prefixed with '#' that groups posts by topic. Chris Messina proposed it on Twitter in August 2007; it became the most widely used folksonomy, a vocabulary made by its users rather than designed in advance.

The right to have personal information removed from search results or erased by those who hold it, established for search engines by the EU Court of Justice in 2014 and as the right to erasure in Article 17 of the GDPR.

Clay Shirky's 2005 essay, from talks at O'Reilly ETech and IMCExpo, arguing that hierarchical classification is a habit of the shelf and that on the Web links and free tagging work better than expert ontologies; the best-known case for folksonomy.

August 2007 essay by Brad Fitzpatrick and David Recordon arguing that the map of who knows whom should be an open, shared asset rather than locked inside each social network.

2009 book by Viktor Mayer-Schönberger arguing that digital memory has made forgetting the exception, and proposing expiration dates for stored information.

Guardian article of June 2013 by Glenn Greenwald and Ewen MacAskill, based on documents from Edward Snowden, revealing the PRISM programme.

Observer and Guardian article of March 2018 by Carole Cadwalladr and Emma Graham-Harrison reporting that a political consultancy obtained data on tens of millions of Facebook users through a quiz app; Facebook then restricted what apps could read.

Paper by Martin Kleppmann and eight Bluesky engineers explaining the design of Bluesky and AT Protocol; published at an ACM CoNEXT workshop in December 2024.

Family of XML formats for syndicating site updates. Netscape's RSS 0.90 (1999) and RSS 1.0 were RDF-based; RSS 2.0 is plain XML.

RDF vocabulary for describing people, their online accounts and who they know; one of the first widely used Semantic Web vocabularies.

Microformat from 2003 for marking up how the person behind a link relates to you, such as friend, colleague or met, using the rel attribute; Google's Social Graph API crawled it.

Conventions for marking up people, events, reviews and similar data with plain HTML class names, without a separate data format.

Protocol created by Brad Fitzpatrick in 2005 that lets people sign in to many sites with an identity they control, a URL rather than a site-specific account; later versions built on OAuth.

RDF vocabulary for describing posts, threads, forums and their authors, so that conversations on blogs, forums and mailing lists can be linked across sites; a W3C Member Submission of June 2007.

Facebook's 2010 vocabulary of meta tags that turn a web page into a rich object when shared; the first version was based on RDFa.

Twitter's meta tags, introduced in 2012, that control how a linked page is previewed in posts; like Open Graph, a platform vocabulary that most websites publish.

W3C Recommendation (2017) for telling any URL that you have linked to it. The receiving site checks that the link really exists and can then show it, giving the Web's one-way links a way back.

W3C Recommendation of February 2017 for describing annotations, such as comments, highlights and tags, in JSON-LD so they can be shared between tools; IIIF uses it for annotations on images.

W3C vocabulary and JSON-LD format for describing social activities such as posts, likes and follows; a Recommendation since May 2017.

W3C Recommendation (2018) for decentralised social networking, used by Mastodon and the wider Fediverse. Its messages are Activity Streams 2.0 in JSON-LD, so the Fediverse runs on Linked Data.

Protocol behind Bluesky. Every account is a DID with a domain name as its handle. Its schema language, Lexicon, deliberately avoids RDF and JSON-LD in favour of strict, versioned schemas.

W3C project of 2001 for shared web annotations: remarks are stored as RDF on separate annotation servers and shown over the page without changing it.

Social network launched in 2003 that dominated the late 2000s and became where many musicians hosted their songs. In 2019 it confirmed that about 50 million songs uploaded before 2015 were lost in a server migration.

Social bookmarking site founded by Joshua Schachter in 2003, where people saved links under their own tags; with Flickr it gave rise to the term folksonomy.

Social network launched in February 2004. Its profiles, pages and 'Log in with Facebook' made a Facebook account a de facto identifier for people and organizations, and its Open Graph protocol turned web pages into objects in its own graph.

Microblogging service launched in 2006, renamed X in 2023. Its usernames serve as identifiers for people and organizations on about 467,000 Wikidata items; it ended free access to its API in February 2023.

US National Security Agency programme, begun in 2007, that collected internet communications from major US companies including Google, Facebook and Apple; disclosed in June 2013 from documents leaked by Edward Snowden.

Google service launched in February 2008 that crawled XFN, FOAF and other public markup to report who links to whom across the Web; retired in April 2012 for lack of use.

Facebook's sign-in for other sites, unveiled as Facebook Connect in July 2008 and generally available from December 2008, which made a Facebook account a login across the Web.

Community, started with the first IndieWebCamp in 2011, of people who publish on their own domains and connect sites with open standards such as microformats and Webmention, instead of relying on platforms.

Decentralised social network built on AT Protocol. It began in 2019 as a research initiative announced by Jack Dorsey at Twitter and became independent in 2021.

American social media company, formerly Facebook, where GraphQL was developed.

Project founded by Dan Whaley in 2011 as a non-profit to build an open annotation layer over the Web; its tool lets anyone annotate any page, publicly or in groups. Development moved to a public benefit corporation in 2019.

Public benefit company incorporated by Jay Graber in October 2021 to develop Bluesky and AT Protocol independently of Twitter.

Technologist who was one of the founders of microformats, with Tantek Çelik.

American programmer who co-edited Activity Streams 2.0 and is listed as an author of ActivityPub.

Software developer who co-edited ActivityPub, the W3C's 2018 standard for decentralised social networking.

American software engineer who led the Bluesky project from 2021, incorporated it as Bluesky Social, and was its CEO until March 2026.

Web developer who edited the W3C Webmention Recommendation (2017).

Web researcher listed as an author of ActivityPub, and later a co-editor of Decentralized Identifiers (DID) 1.0.

American programmer who created LiveJournal and OpenID, co-wrote 'Thoughts on the Social Graph' and, at Google, launched the Social Graph API.

British investigative journalist who reported the Cambridge Analytica story for the Observer and Guardian.

American product designer who proposed the hashtag on Twitter in 2007.

Technologist who co-created FOAF, co-edited RDF Schema, worked on RDF at the W3C and later on schema.org at Google.

American entrepreneur who founded the Hypothesis annotation project in 2011.

Bluesky engineer and co-author of the 2024 paper describing Bluesky and AT Protocol.

American programmer who worked on OpenID and co-wrote 'Thoughts on the Social Graph' in 2007; later at Facebook and the White House.

American web designer and author, one of the three creators of XFN in 2003.

Developer listed as an author of ActivityPub.

Developer at IBM when he co-edited Activity Streams 2.0 with Evan Prodromou.

Software developer who co-edited ActivityPub with Christine Lemmer-Webber.

Irish engineer at the University of Galway who created SIOC and co-edited its specification.

American entrepreneur who founded the social bookmarking site Delicious in 2003.

British technologist who co-created the FOAF vocabulary with Dan Brickley in 2000 and later worked at BBC Research & Development.

American developer who co-founded WordPress and was one of the three creators of XFN in 2003.

Software engineer and Bluesky's CTO; co-author of the 2024 paper describing Bluesky and AT Protocol.

Web standards developer who co-founded the microformats effort and the IndieWeb community, and has worked at Microsoft and Mozilla.

Latvian computer scientist, co-editor of the SIOC specification at DERI Galway.