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Microdata (HTML)

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Title: Microdata (HTML)  
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Subject: Embedded RDF, RDFa, Semantic HTML, Google Searchology, Mod wsgi
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Microdata (HTML)

Microdata is a WHATWG HTML specification used to nest metadata within existing content on web pages.[1] Search engines, web crawlers, and 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 data because it allows search engines to understand the information on web pages and provide more relevant results to users.[2][3] Microdata uses a supporting vocabulary to describe an item and name-value pairs to assign values to its properties.[4] Microdata is an attempt to provide a simpler way of annotating HTML elements with machine-readable tags than the similar approaches of using RDFa and microformats.


  • Vocabularies 1
  • Global attributes 2
  • Example 3
  • Support 4
  • See also 5
  • References 6
  • External links 7


Microdata vocabularies provide the Google, Microsoft and Yahoo! rely on this markup to improve search results. 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.[1] For example, Russian major engine system called Yandex supports main Schema´s microformats like hCard (indicated contact information of the company), hRecipe (indicates the recipe), hRewiev (marking responses) and hProduct (data of goods) and provides its own marking for definition of the terms and encyclopedic articles. The extension of the dictionary was made in order to get rid of problems with transliteration between Cyrillics and Latin. Due this implementation of additional marking parameters and routine use of Schema's vocabulary [5] the indexation of information in Russian-language web-pages became considerably more successful.

Global attributes

  • itemscope – Creates the Item and indicates that descendants of this element contain information about it.[1]
  • itemtype – A valid URL of a vocabulary that describes the item and its properties context.
  • itemid – Indicates a unique identifier of the item.
  • itemprop – 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 URLs using the a element and its href attribute, the img element and its src attribute, or other elements that link to or embed external resources.[1]
  • itemref – Properties that are not descendants of the element with the itemscope attribute can be associated with the item using this attribute. Provides a list of element ids (not itemids) with additional properties elsewhere in the document.[1]


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

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 I live at 1234 Peach Drive, Warner Robins, Georgia.

Here is the same markup with added

  • Microdata — HTML5 Draft Standard,  
  • HTML Microdata W3C Working Group Note
  • Usability testing HTML5, 2009-10-04 , about how some of the design decisions for microdata were made
  • Almaer, Dion (2009-05-11), Hixie discusses the addition of HTML5 "microdata", Ajaxian 
  • HTML5 Microdata Specs, 
  • GetSchema Annotating HTML5 with Microdata. An Example Wiki.
  • Live Microdata, a tool to interactively edit and extract the Microdata embedded in HTML
  • Microdata generator, Web based Microdata rich snippet generator

External links

  1. ^ a b c d e Microdata — HTML5 Draft Standard
  2. ^ MicroData - The Future of Search Engine Relevance and Optimization (SEO)
  3. ^
  4. ^ , Dive Into HTML5“Distributed,” “Extensibility,” And Other Fancy Words
  5. ^ Semantic markup deployment in Russia
  6. ^ Documentation
  7. ^ Type Hierarchy
  8. ^ Turtle RDFS Schema
  9. ^ a b , Google webmaster centralRich snippets (microdata, microformats, RDFa)
  10. ^ Rich Snippet display clarification
  11. ^ Types of Rich Snippets (YouTube: Google Webmasters Channel)
  12. ^ Opera 11.60 for Windows changelog
  13. ^ MicrodataJS


See also

  • Libraries: MicrodataJS[13] is a JavaScript library and jQuery plugin that emulates the DOM API.
Browser Version Support
Maxthon Yes
Opera (Presto) 11.60 Yes
Opera (Blink) 15 No
Firefox 16 Yes
Chrome No
Internet Explorer No
Safari No
  • Servers: Google can[10] use microdata in its result pages.[9] It is the preferred snippet format for the Google+ social network.[11]
  • Browsers: As of December 2013, notable browsers that added support for the Microdata DOM API, are:[12]


   name = John Doe
   jobTitle = graduate research assistant
   affiliation = University of Dreams
   additionalName = Johnny
   url =
   address = Item(1)
Item 1
   streetAddress = 1234 Peach Drive
   addressLocality = Warner Robins
   addressRegion = Georgia

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.[9]

As the above example shows, Microdata items can be nested. In this case an item of type is nested inside an item of type

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
I live at 1234 Peach Drive, Warner Robins, Georgia.

Microdata: [8][7][6]

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