Micro Markup (or Structured Data) is a system of standardized tags and attributes that are added to the HTML code of a web page to define the semantic meaning and type of information in its content. The most popular standard is Schema.org, which is a joint effort of Google, Bing, Yandex and Yahoo.
Conceptually, micro markup is a language for structuring information, designed to communicate with machines. It helps search engines understand contextually what the content of a page is – whether it is a recipe, review, product, event, business address or other. This knowledge allows search engines to present the information in a rich, structured and attractive way in the SERP.
Implementing micro markup is a key element of technical SEO. Its main function is to create Rich Results – such as rating stars, product photos or cooking times – which significantly improve the visibility and click-through rate (CTR) of a page in search results.