Linking

How do things connect?

tension: Easy, one-way, breakable links (the Web) against two-way, unbreakable ones (Xanadu).
also: Hyperlinking, Hypermedia
scheme: design issues

Threads (3)

Long-running problems under this issue, told step by step. All threads.

Can readers write back? 1960–2018 open 7 steps
Can readers attach comments, corrections and links to someone else's page, where other readers will see them?
One-way or two-way links 1945–2018 reopened 7 steps
Should a link be a cheap one-way pointer that can break, or a maintained two-way relationship?
Page or thing? 1998–2012 largely settled 9 steps
When you look up an http URI, have you got the thing it names, or a document about that thing?

Who answered it

This issue's row of the map: which traditions' works mainly answer it, and the earliest from each.

Works on this issue by tradition
tradition	works	earliest
Hypertext	17	As We May Think 1945
Knowledge representation
Databases	2	Linked Movie Database 2009
Machine learning
Web standards	20	Information Management: A Proposal 1989
Search
Social web	3	Annotea 2001
Open knowledge
Decentralized web	1	Webmention 2017
Libraries, archives and museums	1	International Image Interoperability Framework 2012
Life sciences
Media	5	BBC Music and Programmes linked data 2007
Geospatial
Commerce and supply chain
Government and law
Finance
Industry and engineering

7 of 17 traditions have taken up this question as a work's main issue; a work in several traditions counts in each. Same counts as the full map.

Timeline

Works on this question, its main or a secondary one, each shown once in date order; filter by tradition to follow one community. Bars run from start to end where both are known; marks people, projects and organizations still active. 3 entries have no date and are not shown. Hover over or focus an entry to draw its links. Scroll sideways, or use the decades above.

Lineage (31)

Works whose main question this is, by type, oldest first.

Concepts 5

Memex 1945 concept vision
Hypothetical desk-sized device for storing books, records and letters on microfilm and joining them into 'associative trails'. It was never built.
Hypertext 1965 concept technique
Text containing links that let a reader jump to other text. Ted Nelson coined the word in the 1960s; the idea goes back to the memex.
Transclusion 1980 concept technique
Including part of one document in another by reference, so the same content appears in both places and stays linked to its source. Ted Nelson coined the term in 1980.
Linked Data 2006 concept principle
Way of publishing data on the Web with URIs, HTTP and RDF, so that data sets link to one another the way documents do.
Two-way links concept principle
Links that both ends know about, so a document can show what links to it. Central to Xanadu; the Web's links are one-way.

Writings 13

As We May Think 1945 writing ★ seminal vision
Essay in The Atlantic Monthly imagining machines that extend human memory, including the memex, a desk for storing records and linking them by association.
Augmenting Human Intellect: A Conceptual Framework 1962 writing ★ seminal vision
Douglas Engelbart's 1962 SRI report setting out a research programme to use computers to extend human problem-solving, which led to NLS.
A File Structure for the Complex, the Changing and the Indeterminate 1965 writing ★ seminal technique
Ted Nelson's paper at the 1965 ACM national conference, which introduced the word 'hypertext' in print.
Computer Lib / Dream Machines 1974 writing vision
Ted Nelson's self-published two-sided book explaining computers to the public and setting out his ideas for hypertext and Xanadu.
Information Management: A Proposal 1989 writing ★ seminal vision
Tim Berners-Lee's proposal to CERN management for a linked information system. It became the World Wide Web.
Architectural Styles and the Design of Network-based Software Architectures 2000 writing ★ seminal principle
Roy Fielding's 2000 doctoral dissertation at UC Irvine, which defined REST, the architectural style of the Web: resources named by URIs, manipulated through representations over a uniform interface. Most Web APIs since claim descent from it.
Annotea: An Open RDF Infrastructure for Shared Web Annotations 2001 writing
WWW10 paper of May 2001 by José Kahan, Marja-Riitta Koivunen, Eric Prud'hommeaux and Ralph Swick describing Annotea.
Linked Data (Design Issues) 2006 writing ★ seminal principle
Tim Berners-Lee's short Design Issues note setting out four rules for publishing data on the Web with URIs and links.
DBpedia: A Nucleus for a Web of Open Data 2007 writing
2007 paper by the DBpedia founders describing how they extracted Wikipedia's structured content and published it as Linked Data.
Linked Data – The Story So Far 2009 writing ★ seminal
Survey by Bizer, Heath and Berners-Lee of the principles and early growth of the Web of Linked Data.
Media Meets Semantic Web – How the BBC Uses DBpedia and Linked Data to Make Connections 2009 writing ★ seminal technique
2009 ESWC paper by Georgi Kobilarov, Tom Scott, Yves Raimond and colleagues at the BBC and Freie Universität Berlin, describing how BBC Programmes and BBC Music used DBpedia and MusicBrainz identifiers to connect content across the BBC's site.
Linked Movie Data Base 2009 writing technique
2009 workshop paper by Oktie Hassanzadeh and Mariano Consens presenting LinkedMDB, linked open data about films and their links to other datasets.
Linked Data: Evolving the Web into a Global Data Space 2011 writing principle
Book by Tom Heath and Christian Bizer setting out the Linked Data principles and how to publish and use Linked Data.

Standards 5

HTML 1991 standard ★ seminal
HyperText Markup Language, the markup of Web pages, whose anchor element carries the Web's links. Berners-Lee first described it in the informal 'HTML Tags' document in late 1991; HTML 2.0 was published as RFC 1866 in November 1995.
HTTP 1991 standard ★ seminal
Hypertext Transfer Protocol: the Web's request–response protocol for fetching a resource by its URL. Berners-Lee's first version was written up in 1991; HTTP/1.0 and 1.1 followed as IETF RFCs. Looking up a URI to get data about the thing it names depends on it.
International Image Interoperability Framework 2012 standard ★ seminal
Shared web APIs for digitised images, proposed in late 2011 by research libraries including the British Library, Stanford, the Bodleian and the BnF. Its Image API (2012) serves zoomable images, and its Presentation API (2013) describes books and artworks as JSON-LD manifests, so any viewer can show any library's images.
Webmention 2017 standard
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.
Web Annotation Data Model 2017 standard
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.

Projects 8

Project Xanadu 1960 project ★ seminal
Ted Nelson's hypertext project, begun in 1960, aiming at a 'docuverse' with two-way links and transclusion. Only partial versions have been released.
NLS 1962 project ★ seminal
Douglas Engelbart's oN-Line System at SRI, with hypertext links, a mouse and shared screens; publicly shown on 9 December 1968.
World Wide Web 1990 project ★ seminal
Hypertext system of documents linked by URLs and served over HTTP, built by Tim Berners-Lee and Robert Cailliau at CERN from 1990.
Annotea 2001 project
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.
DBpedia 2007 project ★ seminal
Project that extracts structured data from Wikipedia infoboxes and publishes it as Linked Data; an early hub of the Linked Open Data cloud.
BBC Music and Programmes linked data 2007 project
The BBC's pages for every programme (from 2007) and every artist (beta from July 2008), each a web page and an RDF description. Artists were keyed on MusicBrainz identifiers and linked to DBpedia, so a public broadcaster built on fan-made data.
Linked Movie Database 2009 project
Linked open data about films, built at the University of Toronto and presented in April 2009, with links from its films to DBpedia and other datasets.
DBTropes 2009 project
Linked data wrapper for TV Tropes, announced in December 2009, that turns the wiki's pages into RDF linking works of fiction to the tropes they use; by November 2010 about 6,000 of its 16,000 items were linked to DBpedia, and users could correct the extraction.

Also bears on this (21)

Concepts 2

Linked Open Data 2010 concept ★ seminal principle
Linked Data published under an open licence. Berners-Lee's 2010 five-star scheme rates open data from 'available in any format' up to 'linked to other data'.
Dereferenceable URI concept principle
URI that can be looked up over HTTP to get data about the thing it names, which in turn links to further URIs: 'follow your nose'.

Writings 7

Traité de documentation 1934 writing ★ seminal vision
Paul Otlet's treatise on organising documents and knowledge, setting out the field he called documentation.
Cool URIs don't change 1998 writing ★ seminal principle
Tim Berners-Lee's 1998 note arguing that a URI, once published, should keep working indefinitely, and that breaking links is a choice made by poor design rather than an accident of technology.
The Anatomy of a Large-Scale Hypertextual Web Search Engine 1998 writing ★ seminal technique
Brin and Page's 1998 paper describing Google and PageRank, which ranks pages by the links pointing to them; it showed that the Web's link structure could serve as a signal of authority, with no metadata needed from publishers.
httpRange-14 resolution 2005 writing ★ seminal technique
Roy Fielding's June 2005 message announcing the W3C TAG's answer to httpRange-14: a URI that answers with a 2xx response names an information resource, while one that answers with a 303 redirect may name anything.
Cool URIs for the Semantic Web 2008 writing ★ seminal technique
W3C Interest Group Note (2008) giving publishers two recipes for URIs that name things rather than pages: hash URIs, and 303 redirects based on the httpRange-14 resolution.
Executing SPARQL Queries over the Web of Linked Data 2009 writing technique
ISWC 2009 paper by Hartig, Bizer and Freytag proposing link-traversal querying: a SPARQL query is answered by following links and looking up URIs as it runs, so the data sources need not be known in advance.
Scholarly Context Not Found: One in Five Articles Suffers from Reference Rot 2014 writing ★ seminal
2014 PLoS ONE study of millions of web links in scholarly articles, finding that about one in five articles cites web resources that have since vanished or changed: link rot measured at scale.

Standards 3

Architecture of the World Wide Web, Volume One 2004 standard ★ seminal
W3C Technical Architecture Group's account of the Web's architecture: identifying resources by URI, interacting with them through representations, and data formats; a W3C Recommendation since 15 December 2004.
Linked Data Platform 2015 standard
W3C Recommendation of 26 February 2015 setting rules for reading and writing Linked Data with ordinary HTTP operations, so resources and containers behave like a familiar REST API; Solid builds on it.
GS1 Digital Link 2018 standard ★ seminal
GS1 standard for writing product identifiers such as GTINs as web URIs, so that a barcode or QR code on a pack resolves to information about the product; ratified in August 2018. It puts Linked Data identifiers on everyday goods.

Projects 9

HyperCard 1987–2004 project ★ seminal
Apple's programmable card-and-stack application for the Macintosh, written by Bill Atkinson. It put linked, scriptable documents in the hands of ordinary users.
Wayback Machine 2001 project ★ seminal
The Internet Archive's public archive of the Web, open since 25 October 2001 and built from crawls going back to 1996; for many dead links and vanished sites it is the only copy left, kept by a nonprofit funded mainly by donations and grants.
UniProt 2002 project
Database of protein sequences and functions run since 2002 by a consortium of the EBI, SIB and PIR; it publishes its data as RDF with a public SPARQL endpoint.
GeoNames 2005 project ★ seminal
Database of more than 25 million place names, founded in 2005 and published under a Creative Commons attribution licence. Each place has a stable URI that returns a web page or RDF, with links to Wikipedia, which made it the usual place identifier in linked data.
Linked Open Data cloud diagram 2007 project ★ seminal
Diagram of datasets published as Linked Data and the links between them, first drawn in 2007 with DBpedia at its centre.
Google Social Graph API 2008–2012 project
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.
New York Times linked open data 2009 project
The New York Times's release of its subject headings as linked open data, beginning with about 5,000 people's names on 30 October 2009, mapped by hand to DBpedia and Freebase.
legislation.gov.uk 2010 project
The UK's official online statute book, run by The National Archives and launched in 2010, which publishes every law as a web page and as data, with each page's data a URI suffix away, and exposes the statute book as linked data.
Pleiades project
Open gazetteer of ancient places, built from the Barrington Atlas of the Greek and Roman World by NYU's Institute for the Study of the Ancient World and the Ancient World Mapping Center; each place has a stable URI, and its data is CC BY.

People and organizations (31)

Linked to works on this question; the number counts those works.

Tim Berners-Lee (6) · Christian Bizer (5) · Ted Nelson (5) · Douglas Engelbart (3) · Georgi Kobilarov (3) · World Wide Web Consortium (3) · Jens Lehmann (2) · Mariano Consens (2) · Oktie Hassanzadeh (2) · Richard Cyganiak (2) · Roy Fielding (2) · Sören Auer (2) · Tom Heath (2) · Zachary Ives (2) · Aaron Parecki · BBC · Benjamin Young · CERN · DARPA · Eric Prud'hommeaux · Hypothesis · José Kahan · Malte Kiesel · Marja-Riitta Koivunen · Paolo Ciccarese · Ralph Swick · Robert Cailliau · Robert Sanderson · SRI International · Vannevar Bush · Yves Raimond