Microdata is a type of specification language that is embedded within HTML content to improve machine readability, annotate elements and analyze web pages. This type of markup language assigns labels to identify individual pieces of content, allowing search engines to highlight or emphasize more relevant information. For example, the use of microdata could point users in the direction of a product's rating without having to scroll through the entire page.
The website, Schema.org, was established by major search engine operators Google, Microsoft, Yahoo and Yandex to provide technical documentation and HTML code for organizations to take advantage of microdata.
The language used for microdata can be understood by developers that are familiar with HTML/CSS. Similar to metadata, it is written by wrapping a snippet of code with a machine-readable Schema language tag that does not impact the syntax of the browser or document. Types of information that can use the microdata language tags are images, authors, publication dates, headlines, breadcrumbs, reviews and format types.
Successfully implementing microdata can improve search engine optimization (SEO) rankings and user readability as well as click-through rates. Google's Structured Data Testing Tool provides web developers with the ability to see a website through Google's algorithm in order to analyze microdata results.