Structured Data is a term used from the semantic Internet. It allows search engines to precisely classify structured information from webpages and to additionally enrich it.
In order to be able to work with structured data, site operators must use special formats and markups which are uniformly defined. The resource description framework (RDF), various microformats, microdata, and data highlighters are suitable for this purpose. If the data on a website is structured accordingly, search engines such as Google or Bing can specifically categorize them and supplement them with semantics. Google Webmaster Help explains how structured data works in this YouTube video Introduction to Rich Snippets.
Structured Data is used to create links between information. In practice, structured data is often utilized in rich snippets. This is more detailed information, which is displayed in the SERPs in addition to the regular search result. This may look like this:
Google has been developing structured data for some time. During 2012, the company introduced two new tools to facilitate the use of structured data and, in particular, rich snippets. The Structured Data Dashboard in Google Search Console, assists website operators in evaluating the effectiveness of their rich snippets.
The Google Data Highlighter, on the other hand, allows you to tag data fields of a webpage using a mouse click. Next, the information obtained can be prepared in an appealing manner, for example, with the additional display of the search results or the graphical representation in a Google Knowledge Graph.
Structured data is not a novel phenomenon, but has been an integral part of search engine optimization for years. Although it is not defined as a ranking factor by search engines, they use the additional information. Site operators also benefit from better click rates. The semantic web is going to be of great importance in the future. Therefore, search engine optimizers should start working with structured data as of now.