View source for Web annotation

{{Short description|Annotations on web-based resources}}
{{Update|date=February 2015}}

'''Web annotation''' can refer to online [[annotation]]s of web resources<!--([[#Annotation of web resources|web annotation]])--> such as [[web page]]s or parts of them, or a set of [[World Wide Web Consortium|W3C]] [[W3C recommendation|standards]]<!--([[#Web Annotation standard|Web Annotation]])--> developed for this purpose. The term can also refer to the creations of annotations on the [[World Wide Web]] and it has been used in this sense for the annotation tool INCEpTION,<ref>{{cite web|author=Inception |url=https://inception-project.github.io/ |title=Welcome |publisher=Inception-project.github.io |date=2022-07-30 |accessdate=2022-08-07}}</ref> formerly WebAnno.<ref>{{cite web|url=https://webanno.github.io/webanno/|title = Welcome}}</ref> This is a general feature of several tools for [[Annotation#Text documents|annotation in natural language processing]] or [[Annotation#Textual scholarship|in the philologies]].

== Annotation of web resources ==

With a web annotation system, a user can add, modify or remove information from a Web resource without modifying the resource itself. The annotations can be thought of as a layer on top of the existing resource, and this annotation layer is usually visible to other users who share the same annotation system. In such cases, the web annotation tool is a type of [[social software]] tool. For Web-based text annotation systems, see [[Text annotation]].

Web annotation can be used for the following purposes:

* to rate a Web resource, such as by its usefulness, user-friendliness, suitability for viewing by minors.
* to improve or adapt its contents by adding/removing material (like [[wiki]]).
* as a [[Collaborative software|collaborative]] tool, e.g. to discuss the contents of a certain resource.
* as a medium of artistic or social criticism, by allowing Web users to reinterpret, enrich or protest against institution or ideas that appear on the Web.
* to quantify transient relationships between information fragments.
*to save, retain and synthesize selected information.

Annotations can be considered an additional layer with respect to comments.  Comments are published by the same publisher who hosts the original document.  Annotations are added on top of that, but may eventually become comments which, in turn, may be integrated in a further version of the document itself.<ref>{{cite web |url=https://www.w3.org/annotation/diagrams/annotation-architecture.svg |title=Web Annotation Architecture |last=Schepers |first=Doug |publisher=[[W3C]] |access-date=29 July 2016}}</ref>

== Web Annotation standard ==

In the Web Annotation standard,
{{Quote|text=[a]n annotation is considered to be a set of connected resources, typically including a body and target, and conveys that the body is related to the target. The exact nature of this relationship changes according to the intention of the annotation, but the body is most frequently somehow "about" the target. (...) The (...) model supports additional functionality, enabling content to be embedded within the annotation, selecting arbitrary segments of resources, choosing the appropriate representation of a resource and providing styling hints to help clients render the annotation appropriately.|author=Robert Sanderson, Paolo Ciccarese, Benjamin Young (eds.)|title=Web Annotation Data Model, W3C Recommendation 23 February 2017|source=https://www.w3.org/TR/annotation-model/}}

[[File:Web-anno-intro.png|thumb|Basic view on the Web Annotation data model]]

The basic data structures of Web Annotation are 
* target (the element being annotated, e.g., a web document or a part of it),
* body (the content of the annotation, e.g., a string value), and
* annotation (the element that serves to relate body and target of an annotation)

The body can be a literal value or structured content (a URI). The target can be identified by an URI (e.g., fragment identifiers) and/or a selector that defines a domain-, resource- or application-specific access protocol, e.g., offset-based, XPath-based, etc.

Web Annotation was standardized on February 23, 2017 with the release of three official Recommendations by the W3C Web Annotation Working Group:<ref>{{cite web|url=https://w3c.github.io/web-annotation/|title = Deliverables of W3C's Web Annotation Working Group}}</ref><ref name="Whaley2017">{{cite web| last = Whaley| first = Dan| title = Annotation Is Now a Web Standard| work = [[Hypothes.is]]| date = February 24, 2017| url = https://web.hypothes.is/blog/annotation-is-now-a-web-standard/}}</ref>

*    Web Annotation Data Model<ref>{{cite web|url=http://www.w3.org/TR/annotation-model/|title = Web Annotation Data Model}}</ref>
*    Web Annotation Vocabulary<ref>{{cite web|url=http://www.w3.org/TR/annotation-vocab/|title = Web Annotation Vocabulary}}</ref>
*    Web Annotation Protocol<ref>{{cite web|url=http://www.w3.org/TR/annotation-protocol/|title = Web Annotation Protocol}}</ref>

These recommendations were accompanied by additional working group notes that describe their application:

*    Embedding Web Annotations in HTML<ref>{{cite web|url=http://www.w3.org/TR/annotation-html/|title = Embedding Web Annotations in HTML}}</ref>
*    Selectors and States<ref>{{cite web|url=http://www.w3.org/TR/selectors-states/|title = Selectors and States}}</ref>

The Web Annotation data model is also provided in machine-readable form as the Web Annotation ontology.<ref>{{cite web|url=https://www.w3.org/ns/oa#|title = Web Annotation Vocabulary}}</ref>
Note that this ontology defines the Web Annotation namespace (<code>https://www.w3.org/ns/oa#</code>), and that this namespace is conventionally abbreviated as <code>oa</code>. This is the abbreviation for ''Open Annotation'', a W3C Community Group whose specifications formed the basis for the Web Annotation standard.<ref>{{cite web|url=https://www.w3.org/community/openannotation/|title = Open Annotation Community Group}}</ref>

Web Annotation supersedes other standardization initiatives for annotations on the web within the W3C, e.g., the earlier [[Annotea]] project discontinued after 2003.<ref>{{Cite web |title=Semantic Web Activity: Advanced Development / Annotation, Collaboration and Automated Knowledge Access |url=https://www.w3.org/2000/01/sw/#L3028}}</ref><ref>{{Cite web |title=Annotea project |url=https://www.w3.org/2001/Annotea/Overview.html |access-date=2023-11-01 |website=www.w3.org}}</ref>

=== Related specifications ===

Web Annotation can be used in conjunction with (or as an alternative to) [[fragment identifier]]s that describe how to address elements within a web document by means of [[Uniform Resource Identifier|URI]]s. These include

* RFC 5147 (URI fragment identifiers for the text/plain media type)<ref>{{Cite journal|url=https://tools.ietf.org/html/rfc5147|title = Rfc5147| year=2008 | doi=10.17487/RFC5147 | last1=Wilde | first1=E. | last2=Duerst | first2=M. | url-access=subscription }}</ref>
* RFC 7111 (URI fragment identifiers for the text/csv media type)<ref>{{Cite journal|url=https://tools.ietf.org/html/rfc7111|title = Rfc7111|date = January 2014|last1 = Hausenblas|first1 = Michael|last2 = Wilde|first2 = Erik|last3 = Tennison|first3 = Jeni| doi=10.17487/RFC7111 |url-access = subscription}}</ref>
* RFC 8118 (URI fragment identifiers for the application/pdf media type)<ref>{{Cite journal|url=https://tools.ietf.org/html/rfc8118#page-3|title=The application/PDF Media Type|date=March 2017|last1=Hardy|first1=Matthew|last2=Masinter|first2=Larry M.|last3=Markovic|first3=Dejan|last4=Johnson|first4=Duff|last5=Bailey|first5=Martin|doi=10.17487/RFC8118 |url-access=subscription}}</ref>
* [[Scalable Vector Graphics|SVG]] fragment identifiers<ref>{{cite web|url=https://www.w3.org/TR/SVG11/linking.html#SVGFragmentIdentifiers|title=Linking – SVG 1.1 (Second Edition)}}</ref>
* [[XPointer]] (for addressing components of XML documents)<ref>{{cite web|url=https://www.w3.org/TR/xptr-framework/|title = XPointer Framework}}</ref>
* Media Fragments (for addressing components of media files)<ref>{{cite web|url=https://www.w3.org/TR/media-frags/|title = Media Fragments URI 1.0 (Basic)}}</ref>

Other, non-standardized fragment identifiers are in use, as well, e.g., within the NLP Interchange Format.<ref>{{cite web|url=http://bpmlod.github.io/report/nif-corpus/index.html|title = Guidelines for Linked Data corpus creation using NIF}}</ref>

Independently from Web Annotation, more specialized data models for representing annotations on the web have been developed, e.g., the NLP Interchange Format (NIF)<ref>{{cite web|url=https://site.nlp2rdf.org/ |title=Nlp2rdf.org |publisher=Site.nlp2rdf.org |date= |accessdate=2022-08-07}}</ref> for applications in language technology. In early 2020, the [[W3C]] Community Group "Linked Data for Language Technology" launched an initiative to harmonize these vocabularies and to develop a consolidated RDF vocabulary for linguistic annotations on the web.<ref>{{cite web|url=https://github.com/ld4lt/linguistic-annotation|title = Ld4lt/Linguistic-annotation|website = [[GitHub]]|date = 31 May 2021}}</ref>

== Web Annotation Systems ==

===Comparison of web annotation systems===
Many of these systems require software to be installed to enable some or all of the features below. This fact is only noted in footnotes if the software that is required is additional software provided by a third party.
{{sort-under}}
{| class="wikitable sortable sort-under"
|-
! Annotation system !! {{verth|Private notes}} !! {{verth|Private group notes}} !! {{verth|Public notes}} !! {{verth|Notification}} !! {{verth|Highlighting}} !! {{verth|Formatted text}} !! Archives
! Viewing annotations !! API
! Open Source 
! {{verth|implements/exports/imports<br/>Web annotation standard}}!! Notes
|-
| [[A.nnotate]] || {{yes}} || {{yes}} || {{no}} || {{yes}}<ref>See [http://a.nnotate.com/notifications.html A.nnotate notifications]</ref> || {{yes}} || {{no}} || {{yes}}
|
| {{yes}}
| {{no}} (proprietary)
| {{Unknown}}|| Can annotate PDF, ODF, .doc, .docx, images, as well as web pages (but only a limited number in the free version)
|-
|Annotorius<ref>{{Cite web |title=Annotorious {{!}} JavaScript image annotation library |url=https://annotorious.github.io/ |access-date=2023-10-18 |website=annotorious.github.io}}</ref>
|
|
|
|
|
|
|{{yes}}, via Google Firebase plugin<ref>{{Cite web |title=Getting Started: Storing Annotations |url=https://recogito.github.io/annotorious/getting-started/storing-annotations |access-date=2023-10-18 |website=recogito.github.io}}</ref>
|
|{{yes}}
|{{yes}} (BSD)<ref>{{Cite web |title=Annotorious {{!}} About |url=https://annotorious.github.io/about/ |access-date=2023-10-18 |website=annotorious.github.io}}</ref>
|{{yes}}<ref>{{Cite web |title=Annotorious & Web Annotation |url=https://recogito.github.io/annotorious/getting-started/web-annotation |access-date=2023-10-18 |website=recogito.github.io}}</ref>
|JavaScript image annotation library and plugin to [[Seadragon Software|OpenSeadragon]], also supports simple text annotations
|-
| [[Diigo]] || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{no}} || {{yes}}
|
| {{yes}}
| {{no}} (proprietary)
| {{Unknown}}|| Public annotations are only allowed for established{{Definition needed|date=March 2016}} users. Group tag dictionary feature to encourage tagging consistently within a group.
|-
| [[Hypothes.is]] || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} ||
|Chrome, via.hypothes.is
|{{yes}}
| {{yes}} (MIT, BSD)
| {{No}},<ref>{{Cite web |title=Hypothesis API documentation (v1) |url=https://h.readthedocs.io/en/latest/api-reference/v1/ |access-date=2023-10-18 |website=h.readthedocs.io}}</ref> but listed on Web Annotation wiki|| In February 2015, different features were announced,<ref>{{cite web |title=Trello |url=https://hypothes.is/roadmap/ |website=hypothes.is}}</ref> such as private group annotation, semantic tagging, moderation, etc. Web Annotation integration was discussed in 2014.<ref>{{Cite web |last=bigbluehat |date=2014-10-15 |title=Open Annotation RDFa using Hypothes.is JSON |url=https://web.hypothes.is/blog/open-annotation-rdfa-using-hypothes-is-json/ |access-date=2023-10-18 |website=Hypothesis |language=en-US}}</ref><ref>{{Cite web |title=Implementations - Web Annotation Wiki |url=https://www.w3.org/annotation/wiki/Implementations |access-date=2023-10-18 |website=www.w3.org}}</ref>
|-
| [[Org-mode]] (with extensions) || {{yes}} || {{no}} || {{no}}<ref>Technically, public annotations are possible via the "publish to HTML" feature of org mode -- but no method for notifications or discovery of public annotations written by others is currently known.</ref> || {{No}}<ref>But local annotations can be exposed to a firefox browser using [http://orgmode.org/worg/org-devel.html Fireforg].</ref>|| {{no}} || {{yes}} || {{no}}
|
| {{yes}}
|
| {{Unknown}}|| Emacs-based; requires technical knowledge to set up; not as user-friendly as some other solutions; non-Latin characters allowed in notes but not in tags
|-
|Recogito<ref>{{Cite web |title=Semantic Annotation without the pointy brackets |url=https://recogito.pelagios.org/ |access-date=2023-10-18 |website=recogito.pelagios.org}}</ref>
|{{yes}}
|{{yes}}
|{{yes}}
|
|{{yes}}
|
|
|{{yes}}
|{{yes}}
|{{yes}} (Apache)
|{{yes}}
|Annotation of named entities, linking with maps and [[Knowledge graph|knowledge graphs]], developed by the Pelagios network,<ref>{{Cite web |title=Welcome to Pelagios Network |url=https://pelagios.org/ |access-date=2023-10-18 |website=pelagios.org}}</ref> popular in [[Digital humanities|Digital Humanities]]
|}

===Discontinued web annotation systems===
{{Expand list|date=February 2011}}

{| class="wikitable sortable"
|-
! System !! Notes !! Date Discontinued 
|-
| Mosaic Browser 
| An early version of the Mosaic browser was tested with collaborative annotation feature in 1993<ref>{{cite web |last=Andreessen |first=Marc |date=1993-05-31 |title=group annotation server guinea pigs? |url=http://1997.webhistory.org/www.lists/www-talk.1993q2/0416.html |access-date=2017-11-08 |website=webhistory.org}}</ref> but never passed the test state.
| Never passed the test state
|-
| CritLink 
| Perhaps the earliest web annotation system. Developed in 1997–98 by Ka-Ping Yee of the University of California.<ref>{{cite web |last=Yee |first=Ka-Ping |year=2002 |title=CritLink: Advanced Hyperlinks Enable Public Annotation on the Web |id=[[CiteSeerX]]: {{url|1=http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.5.5050|2=10.1.1.5.5050}}}}</ref>  CritLink worked as an HTML "mediator", hence not requiring additional software or browser extensions but having limited support for modern [[JavaScript]]-driven websites.
|
|-
| [[Annotea]] 
| A [[W3C]] project that tried to establish a standard for web annotation. Annotea was conceived as part of the [[semantic web]]. According to the website, Annotea development stalled in October 2005.<ref>{{cite web |title=Annotea project |url=https://www.w3.org/2001/Annotea/}}</ref>
|
|-
| [[ThirdVoice]]
| A system launched in 1999. It was targeted by a campaign called Say No to TV,<ref>{{cite web |title=Say NO To Third Voice! - WEBMASTERS UNITE!! |url=http://worldzone.net/internet/pixelsnttv/index.html |url-status=dead |archive-url=https://web.archive.org/web/20010405170639/http://worldzone.net/internet/pixelsnttv/index.html |archive-date=April 5, 2001}}</ref> led by independent web hosts which likened ThirdVoice to "Web graffiti."<ref>{{cite web |title=The Web's New Graffiti? |url=https://www.wired.com/news/technology/0,1282,20101,00.html |url-status=dead |archive-url=https://web.archive.org/web/20011121120524/https://www.wired.com/news/technology/0,1282,20101,00.html |archive-date=November 21, 2001}}</ref> It was shut in April 2001 because it couldn't generate enough advertising revenue to stay in business.<ref>[http://archive.wired.com/techbiz/media/news/2001/04/42803?currentPage=all Third Voice Trails Off], ''Wired News'', April 4, 2001</ref>
| April 2001
|-
| [[Delicious (website)|Delicious]] 
| Founded in 2003 and provided cloud bookmarks with optional descriptions (a form of annotation) of up to 1000 characters. It was rumoured that it would be shut down in 2010, but it was only actually finally shut down in 2017 when it was acquired by Pinboard, a competitor.
| 2017
|-
| Wikalong
| A Firefox plugin created in 2004 that provided a publicly editable mediawiki page in the margin of any webpage. (It was later accessible in other browsers via a bookmarklet.) Common uses were note-taking and discussion about the website. On Google, the Wikalong margin provided a variety of useful tips and shortcuts for searching. The project was discontinued in 2009 when the storage wiki went offline. It had been suffering from [[Spamdexing|link spam abuse]].<ref>[https://addons.mozilla.org/en-US/firefox/addon/wikalong/ Wikalong Firefox Addon], Oct 1, 2006</ref><ref>{{cite web |title=SEO – SEO-Optimierung |url=http://www.wikalong.org/ |website=www.wikalong.org}}</ref>
| 2009
|- 
| [[Fleck*]] 
| Launched in 2005 with much publicity as a stick-it notes application for the web. A patent, funding and marketing didn't stop it from failing. Discontinued in 2010.<ref>[https://thenextweb.com/socialmedia/2010/05/10/farewell-fleck-com/ Farewell Fleck.com, "The Next Web"], May 10, 2010</ref>
| 2010
|-
| [[stet (software)|stet]] 
| Stet was the [[Gplv3]] comment system.<ref>{{cite web |author=<!--Staff writer(s); no by-line.--> |date=11 May 2011 |title=Comment system |url=http://gplv3.fsf.org/wiki/index.php/Comment_system |access-date=28 July 2016 |publisher=[[Free Software Foundation]]}}</ref>
|
|-
| Crocodoc
| Launched in 2007, dabbled in web page annotation as part of its broader mission. It was originally developed in Adobe Flash. It was acquired by Box.com in 2013<ref>{{cite web |date=9 May 2013 |title=Box acquires Crocodoc to turn all those docs you upload into HTML5 masterpieces |url=https://venturebeat.com/2013/05/09/box-acquires-crocodoc-to-turn-all-those-docs-you-upload-into-html5-masterpieces/ |access-date=12 June 2016 |publisher=[[VentureBeat]]}}</ref> and the web annotation side of it was shut down two years later.<ref>{{cite web |date=5 August 2015 |title=Box is Shutting Down Crocodoc Personal and Webnotes on November 1 |url=https://venturebeat.com/2015/08/05/box-is-shutting-down-crocodoc-personal-and-webnotes-on-november-1/ |access-date=12 June 2016 |publisher=[[VentureBeat]]}}</ref>
| 2009
|-
| [[Blerp]]
| Launched in 2009. A multimedia, extensible tool for annotating web pages with widgets viewable by any other Blerp user.
|
|-
| [[Google Sidewiki]]
| Launched in 2009. A part of Google Toolbar that allowed users to write comments alongside any web page. It was discontinued in December 2011.
| December 2011
|- 
| [[SharedCopy]] 
| An AJAX based web annotation tool that allowed users to mark-up, highlight, draw, annotate, cache, sticky-note and finally share any website.
|- 
| [[Genius (company)#News Genius|Genius Web Annotator]] 
| Formerly knows as News Genius, launched in 2016.<ref>{{cite web |title=News Genius |url=https://genius.com/a/news-genius |access-date=2022-05-27 |website=Genius |language=en}}</ref> As of May 2022, the Chrome and Wordpress extensions are discontinued, and the bookmarklet provided on [https://genius.com/web-annotator the official website] does not work.  As of August 2022, it is not possible to log in and leave new annotations.
|
|}

== See also ==
* [[Comparison of notetaking software]]
* [[Social bookmarking]]
* Some [[reference management software]] packages also support web annotations
* [[Backlinks]]
* [[Online deliberation]]
* [[Perusall]]
* [[Folksonomy]]
* [[Metadata]]
* [[Threaded discussion]]
* [[Virtual graffiti]]
* [[Comparison of software saving Web pages for offline use]]

== References ==
{{reflist}}

== Further reading ==
* {{cite conference |doi=10.1145/1816123.1816125 |chapter=Making Web Annotations Persistent over Time |last1=Sanderson |first1=Robert |last2=Van de Sompel |first2=Herbert |title=Proceedings of the 10th annual joint conference on Digital libraries - JCDL '10 |author-link2=Herbert Van de Sompel |year=2010 |publisher=[[Association for Computing Machinery]] |book-title=Proceedings of JCDL '10, Joint Conference on Digital Libraries |pages=1–10 |arxiv=1003.2643 |isbn=9781450300858 }}
* Signer, Beat: [https://www.academia.edu/193985/An_Architecture_for_Open_Cross-Media_Annotation_Services "An Architecture for Open Cross-Media Annotation Services"], Proceedings of WISE 2009, 10th International Conference on Web Information Systems Engineering, Poznan, Poland, October 2009
* [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.101.1343 On Web Annotations: Promises and Pitfalls of Current Web Infrastructure. Venu Vasudevan and Mark Palmer, Proceedings of the 32nd Hawaii International Conference on System Sciences - 1999]
* [http://www.math.grin.edu/~rebelsky/Blazers/Annotations/Summer1999/Papers/survey_paper.html A Survey of Web Annotation Systems. Rachel M. Heck, Sarah M. Luebke, Chad H. Obermark. 1999.]
* [http://www9.org/final-posters/poster46.html New ways of using Web annotations. Laurent Denoue, Laurence Vignollet.]
* Ricardo Kawase, George Papadakis, Eelco Herder, Wolfgang Nejdl: [http://dl.acm.org/citation.cfm?doid=1810617.1810624 The impact of bookmarks and annotations on refinding information. ACM Hypertext Conference 2010: 29-34]
* Ricardo Kawase, Eelco Herder, George Papadakis, Wolfgang Nejdl: [https://dx.doi.org/10.1007/978-3-642-22810-0_7 In-Context Annotations for Refinding and Sharing]. ''[[Webist]]'' (Selected Papers) 2010: 85-100

==External links==
* [https://www.w3.org/annotation/ W3C Web Annotation Working Group] Recommendations (as of February 23, 2017):
# [http://www.w3.org/TR/annotation-model/ Web Annotation Data Model]
# [http://www.w3.org/TR/annotation-vocab/ Web Annotation Vocabulary]
# [https://www.w3.org/TR/annotation-protocol/ Web Annotation Protocol]
* [https://www.w3.org/annotation/diagrams/annotation-architecture.svg Web Annotation Architecture], W3C's interactive illustration

[[Category:Web annotation| ]]
[[Category:Social software|Web annotation]]
[[Category:Web software]]