Microdata (HTML): Difference between revisions

Revision as of 15:58, 8 December 2019

Latest revision as of 13:14, 6 August 2024

(47 intermediate revisions by 35 users not shown)

Line 1:

{{short description|Specification for metadata in web pages}}

{{Other uses|Microdata (disambiguation)}}

{{HTML}}

'''Microdata''' is a [[WHATWG]] [[HTML]] specification used to nest [[metadata]] within existing content on web pages.<ref name="WHATWG"/> [[Search engines]], [[web crawlers]], and [[Web browser|browsers]] can extract and process Microdata from a web page and use it to provide a richer browsing experience for users. Search engines benefit greatly from direct access to this structured dataMicrodata because it allows them to understand the information on web pages and provide more relevant [[Search engine results page|results]] to users.<ref>{{cite web|url=http://www.lyquix.com/blog-and-news/microdata-the-future-of-search-engine-relevance-and-search-engine-optimization-seo |title=MicroData - The Future of Search Engine Relevance and Optimization (SEO) |publisher=Lyquix.com |access-date= |accessdate=2016-06-30}}</ref><ref>Schema.org http://schema.org/</ref> Microdata uses a supporting vocabulary to describe an item and name-value pairs to assign values to its properties.<ref name="DIVE"/> Microdata is an attempt to provide a simpler way of annotating [[HTML element]]s with machine-readable tags than the similar approaches of using [[RDFa]] and [[microformat]]s.

In 2013, because the W3C HTML Working Group failed to find someone to serve as an editor for the '''Microdata HTML''' specification, its development was terminated with a 'Note'.<ref>{{cite mailing list|url=https://lists.w3.org/Archives/Public/public-html-admin/2013Oct/0018.html |title=WG Decision to publish HTML Microdata as a WG Note |mailing-list=[e-mail] |date=2 Oct 2013 |first=Paul |last=Cotton |accessdateaccess-date=2016-06-30}}</ref><ref>{{cite web|url=http://www.w3.org/TR/microdata/ |title=HTML Microdata |publisher=W3.org |date=23 June 2014 |accessdateaccess-date=2016-06-30}}</ref> However, since that time, two new editors were selected, and five newer versions of the working draft have been published,<ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20170504/|title=HTML Microdata W3C First Public Working Draft 04 May 2017|website=World Wide Web Consortium (W3C)|accessdateaccess-date=2017-09-06}}</ref><ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20170626/|title=HTML Microdata W3C Working Draft 26 June 2017|website=World Wide Web Consortium (W3C)|accessdateaccess-date=2017-09-06}}</ref><ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20171009/|title=HTML Microdata W3C Working Draft 09 October 2017|date=9 October 2017|website=World Wide Web Consortium (W3C)|access-date=16 March 2018}}</ref><ref name=":0">{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20171010/|title=HTML Microdata W3C Working Draft 10 October 2017|date=10 October 2017|website=World Wide Web Consortium (W3C)|access-date=16 March 2018}}</ref> the most recent being [https://www.w3.org/TR/microdata/<abbr>W3C</abbr> Working Draft 26 April 2018].<ref name=":0" />

== Vocabularies ==

Microdata vocabularies do not provide the [[semantics]], or meaning of an Item.<ref>{{Cite web | title = HTML Standard | url = https://html.spec.whatwg.org/multipage/microdata.html | website = Web Hypertext Application Technology Working Group | accessdateaccess-date = 30 December 2016}}</ref> Web developers can design a custom vocabulary or use vocabularies available on the web. A collection of commonly used markup vocabularies are provided by [[Schema.org]] schemas which include: ''Person'', "''Place''", ''Event'', ''Organization'', ''Product'', ''Review'', ''Review-aggregate'', ''Breadcrumb'', ''Offer'', ''Offer-aggregate''. The website schema.org was established by search engine operators like [[Google]], [[Microsoft]], [[Yahoo!]], and [[Yandex]], which use microdata markup to improve search results.<ref>{{cite book|title=HTML5: The missing manual|last=MacDonald|first=Matthew|edition=2nd|publisher=[[O'Reilly and Associates]]|date=2014|isbn=978-1-4493-6326-0}}</ref>{{rp|85}}

For some purposes, an ad-hoc vocabulary is adequate. For others, a vocabulary will need to be designed. Where possible, authors are encouraged to re-use existing vocabularies, as this makes content re-use easier.<ref name="WHATWG"/>

== Localization ==

In some cases, search engines covering specific regions may provide locally-specific extensions of microdata. For example, [[Yandex]], a major search engine in Russia, supports [[microformats]] such as [[hCard]] (company contact information), [[hRecipe]] (food recipe), [[hReview]] (market reviews) and [[hProduct]] (product data) and provides its own format for definition of the terms and encyclopedic articles. This extension was made in order to solve [[transliteration]] problems between the Cyrillic and Latin alphabets. After the implementation of additional parameters from Schema's vocabulary,<ref name="AcademicYan"/> indexation of information in Russian-language web-pages became more successful.

== Global attributes ==

* <code>itemscope</code> – Creates the Item and indicates that descendants of this [[HTML element|element]] contain information about it.<ref name="WHATWG"/>

* <code>itemtype</code> – A valid URL of a vocabulary that describes the item and its properties' context.

* <code>itemid</code> – Indicates a unique identifier of the item.

* <code>itemprop</code> – Indicates that its containing tag holds the value of the specified item property. The property's name and value context are described by the item's vocabulary. Properties values usually consist of string values, but can also use [[URL]]sURLs using the <code>a</code> element and its <code>href</code> attribute, the <code>img</code> element and its <code>src</code> attribute, or other elements that link to or embed external resources.<ref name=WHATWG/>

* <code>itemref</code> – Properties that are not descendants of the element with the <code>itemscope</code> attribute can be associated with the item using this attribute. Provides a list of element idsIDs (not <code>itemid</code>s) with additional properties elsewhere in the document.<ref name="WHATWG"/>

* <code>datetime</code> -– Indicates date or duration as specified by [[ISO 8601]] standard.

== Example ==

The following HTML5 markup may be found on a typical “About” page containing information about a person:

<sourcesyntaxhighlight lang=html5"html">

<sectiondiv> Hello, my name is John Doe, I am a graduate research assistant at

the University of Dreams.

My friends call me Johnny.

You can visit my homepage at <a href="http://www.JohnnyDexample.com/~JohnnyD">www.JohnnyDexample.com/~JohnnyD</a>.

I live at 1234 Peach Drive, Warner Robins, Georgia.</sectiondiv>

</syntaxhighlight>

</source>

Here is the same markup with added [[Schema.org]]<ref>{{cite web|url=http://schema.org/docs/documents.html |title=Documentation |publisher=Schema.org |access-date= |accessdate=2016-06-30}}</ref><ref>{{cite web|url=http://schema.org/docs/full.html |title=Type Hierarchy |publisher=Schema.org |access-date= |accessdate=2016-06-30}}</ref><ref>[{{Cite web |url=http://schema.rdfs.org/all.ttl |title=Schema.org Turtle RDFS Schema] |access-date=2013-05-29 |archive-url=https://web.archive.org/web/20140921103224/http://schema.rdfs.org/all.ttl |archive-date=2014-09-21 |url-status=dead }}</ref> Microdata:

<sourcesyntaxhighlight lang=html5"html">

<sectiondiv itemscope itemtype="http://schema.org/Person">

Hello, my name is

<span itemprop="name">John Doe</span>,

Line 45 ⟶ 46:

<span itemprop="additionalName">Johnny</span>.

You can visit my homepage at

<a href="http://www.JohnnyDexample.com/~JohnnyD" itemprop="url">www.JohnnyDexample.com/~JohnnyD</a>.

<sectiondiv itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">

I live at

<span itemprop="streetAddress">1234 Peach Drive</span>,

<span itemprop="addressLocality">Warner Robins</span>,

<span itemprop="addressRegion">Georgia</span>.

</sectiondiv>

</sectiondiv>

</syntaxhighlight>

</source>

As the above example shows, Microdata items can be nested. In this case, an item of type http://schema.org/PostalAddress is nested inside an item of type http://schema.org/Person.

The following text shows how Google parses the Microdata from the above example code. Developers can test pages containing Microdata using Google's ''Rich Snippet Testing Tool''.<ref name="GoogleRS"/>

<div class="plainlinks">

Item

Type: http://schema.org/Person

Line 65 ⟶ 66:

affiliation = University of Dreams

additionalName = Johnny

url = <nowiki>http://www.johnnydexample.com/~JohnnyD</nowiki>

address = Item(1)

Item 1

Line 72 ⟶ 73:

addressLocality = Warner Robins

addressRegion = Georgia

</div>

The same machine-readable terms can be used not only in HTML Microdata, but also in other annotations such as [[RDFa]] or [[JSON-LD]] in the markup, or in an external [[Resource Description Framework|RDF]] file in a serialization such as [[RDF/XML]], [[Notation3]], or [[Turtle (syntax)|Turtle]].

== Support ==

* Servers: [[Google]] can<ref name=GoogleCan /> use microdata in its [[Search engine results page|result pages]].<ref name=GoogleRS /> It iswas the preferred snippet format for the [[Google+]] social network.<ref>{{cite AV media|url=https://www.youtube.com/watch?v=4W8Ah394bH8 |archive-url=https://ghostarchive.org/varchive/youtube/20211215/4W8Ah394bH8 |archive-date=2021-12-15 |url-status=live|title=Types of Rich Snippets |author=Google Webmasters Channel |medium=Video |date=2011-12-06 |accessdateaccess-date=2016-06-30}}{{cbignore}}</ref>

{{update|section|date=January 2018}}

* Browsers: {{As of|2021|7}}, no major browser supports the Microdata [[Document Object Model|DOM]] [[API]].<ref>{{Cite web|title=Microdata DOM API - Web APIs {{!}} MDN|url=https://developer.mozilla.org/en-US/docs/Web/API/Microdata_DOM_API|access-date=2021-07-05|website=developer.mozilla.org|language=en-US}}</ref> Opera supported it from 11.60 (released in 2011), but since removed its implementation.<ref>{{cite web |author=Opera Software Documentation Team |url=http://www.opera.com/docs/changelogs/windows/1160/ |title=Opera 11.60 for Windows changelog |publisher=Opera.com |date=2011-12-06 |access-date=2016-06-30 |archive-url=https://web.archive.org/web/20141023082043/http://www.opera.com/docs/changelogs/windows/1160/ |archive-date=2014-10-23 |url-status=dead }}</ref> Firefox removed it in version 49.<ref>{{Cite web|title=909633 - Remove HTML Microdata API|url=https://bugzilla.mozilla.org/show_bug.cgi?id=909633|access-date=2021-07-05|website=bugzilla.mozilla.org|language=en}}</ref>

* Servers: [[Google]] can<ref name=GoogleCan /> use microdata in its [[Search engine results page|result pages]].<ref name=GoogleRS /> It is the preferred snippet format for the [[Google+]] social network.<ref>{{cite AV media|url=https://www.youtube.com/watch?v=4W8Ah394bH8 |title=Types of Rich Snippets |author=Google Webmasters Channel |medium=Video |date=2011-12-06 |accessdate=2016-06-30}}</ref>

* Browsers: {{As of|2013|12}}, notable browsers that added support for the Microdata [[Document Object Model|DOM]] [[API]], are.<ref>{{cite web|author=Opera Software Documentation Team |url=http://www.opera.com/docs/changelogs/windows/1160/ |title=Opera 11.60 for Windows changelog |publisher=Opera.com |date=2011-12-06 |accessdate=2016-06-30}}</ref> As of April 2018, Microdata DOM API is deprecated according to Mozilla.<ref>{{cite web|url=https://developer.mozilla.org/en-US/docs/Web/API/Microdata_DOM_API|website=mozilla.org|accessdate=18 April 2018|title=Microdata DOM API}}</ref>

{| class="wikitable"

|-

! Browser !! Version !! Support

|-

| [[Maxthon]] || 5.2.7.100 || {{no}}

|-

| [[Opera (web browser)|Opera]] ([[Presto (layout engine)|Presto]]) || 12.17 || {{yes}}

|-

| Opera ([[Blink (layout engine)|Blink]]) || 15 || {{no}}

|-

| [[Firefox]] || 49 || {{no}}<ref>https://bugzilla.mozilla.org/show_bug.cgi?id=909633</ref>

|-

| [[Google Chrome|Chrome]] || 71.0.3578.98 || {{no}}

|-

| [[Internet Explorer]] || 8 || {{no}}

|-

| [[Safari (web browser)|Safari]] || || {{no}}

|-

| [[Microsoft Edge]] || || {{no}}

|}

* Libraries: MicrodataJS<ref name=MicrodataJS/> is a [[JavaScript]] library and [[jQuery]] plugin that emulates the DOM API.

== See also ==

* [[Semantic web]]

* [[Microformat]]

;* [[RDFa Lite]]

;* [[JSON-LD]]

* [[CP/LD|CP/LD (Content Profile/Linked Document)]]

* [[Semantic HTML]]

* [[Semantic social network]]

Line 112 ⟶ 91:

==References==

{{Reflist|30em|refs=

<ref name="WHATWG">{{cite web|url=http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html |title=Microdata — HTML Draft Standard |publisher=Whatwg.org |access-date= |accessdate=2016-06-30}}</ref>

<ref name="AcademicYan">{{cite web|url=https://www.academia.edu/6732371/Untangling_the_Semantic_Web_Microdata_use_in_Russian_video_content_delivery_sites.html |title=Semantic markup deployment in Russia |publisher=Academia.edu |accessdateaccess-date=2016-06-30}}</ref>

<ref name="GoogleCan">{{cite web|url=httphttps://www.google.com/support/webmasters/bin/answer.py?answer=99170 |title=Rich Snippet display clarification |publisher=Google.com |date=2016-06-22 |accessdateaccess-date=2016-06-30}}</ref>

<ref name="GoogleRS">{{cite web|url=https://developers.google.com/structured-data/testing |title=Rich snippets (microdata, microformats, RDFa) |publisher=Google webmaster centralInc. |date=2016-05-17 |accessdateaccess-date=2016-06-30}}</ref>

<ref name="DIVE">{{cite web|url=http://diveintohtml5.info/extensibility.html |title="Distributed," "Extensibility," And Other Fancy Words |publisher=Diveintohtml5.info |access-date= |accessdate=2016-06-30}}</ref>}}

<ref name="MicrodataJS">{{cite web|url=https://github.com/foolip/microdatajs |title=MicrodataJS |publisher=Github.com |date=2011-12-12 |accessdate=2016-06-30}}</ref>}}

== External links ==

* {{citation |url=https://html.spec.whatwg.org/multipage/microdata.html |title=Microdata &mdash; HTML Draft Standard |publisher=[[Web Hypertext Application Technology Working Group|WHATWG]]}}

* {{citation |url=https://www.w3.org/TR/microdata/|title=W3C HTML Microdata Working Group Note |publisher=[[W3C]]}}

* {{citation |url=http://ajaxian.com/archives/hixie-discusses-the-addition-of-html5-microdata |title=Hixie discusses the addition of HTML5 "microdata" |date=2009-05-11 |first=Dion |last=Almaer |publisher=Ajaxian|archive-url=https://web.archive.org/web/20091212053447/http://ajaxian.com/archives/hixie-discusses-the-addition-of-html5-microdata |archive-date=2009-12-12 }}

* {{citation |url=http://www.data-vocabulary.org |title=HTML5 Microdata Specs |publisher=Data-Vocabulary.org}}