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The microdata they are additional markups for a type of information from HTML, Atom documents, RSS feeds or feeds, as well as XML files. Microdata mark specific information indicating something about the item described.

This is done by specifying certain properties that are specified in the corresponding micro-format. A property is a name-value pair. A collection of properties is described as a post. Types of information such as people, places, events, reviews, or stores can be identified that way.

General information

Microdata is HTML5 compliant and can be integrated into source code using certain attributes. Other names for microdata are structured data or semantic HTML. However, microdata is not a particular format for this type of markup, but rather the general term for it. RDFas, schemas or individual microformats such as HCard, hProduct, hReview or Geo can be categorized under the same theme, but should be considered syntactic variants. The goal is to identify the data so that both search engines and users have an indication of its importance.

HCard as an example of a micro-format

The HCard micro-format can be used on a website, for example, to display someone's business card. In this way, properties such as name, street, postal code, place, and various contact options are listed and displayed accordingly. HCards cards can also be used by companies and institutions. In HTML5 a business card is referred to as a person and in some cases attention must be paid to the difference between microdata and microformats, even if these formats are compatible.

Advantages of microdata

The decisive advantage of microdata is the description of semantic information, that is, the information about the meaning of the respective data. Microformats are therefore one of many steps towards a semantic web in which the meaning of the data is represented in various ways. However, it must be consistent with the marking of the data and use only a microformat or specification.


Microdata allow the marking of a variety of information. Depending on the type, the respective format can be chosen. The syntax of the microdata is specified in the W3C HTML microdata specifications. The microdata are compatible with other microformats such as RDF and can also be processed through a programming interface. At the same time, it can be used with JSON, the JavaScript object model. Therefore the microdata can be exchanged between the client and the server. For example, in interactive apps.

Possible microdata

  • Person
  • Organization
  • Event
  • Venue, local business, restaurant
  • Product, offer, aggregate offer
  • Review, review added

Practical relevance

Here is an example of markup with microdata in HTML source code. The person, Michael Smith, will be described with a compilation of name-value pairs. Before using these properties, they must be assigned a type. This is done with the position type. Itemscope in turn indicates that an information package follows, which is contained in the div tag. The person format can also be used to represent HCard and vCard information.

My name is Michael Smith, my nickname is Mike. My website is: I live at Boston in Massachusetts and work as aengineeratSmith & Co ..

Relevance for SEO

Microdata not only represents new data markup options, it has also been used in search engine optimization for some time. The Rel tag is an example. While Rel-nofollow is used to distance itself from third-party content, Rel-author has recently been used to characterize the creator of the content.

Strictly speaking, these are also microformats and their relevance should not be underestimated in the field of SEO. In particular, authorship marking gained importance recently, even though now the author of a document no longer appears with a photo in search results.

At the same time, various microformats represent machine-readable content and thus provide search engines with important information about the content. This can have the side effect that some types of information will be displayed in a special way in the SERPs and thus can increase the CTR.

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