What is Structured Data and Why You Need To Know Now: "Structured Data Outline
I. Definition: Data on a website that can be classified by a search engine.
II. 4 Types of Structured Data: Schema.org – is a collaborative structured data effort by Google, Microsoft, and Yahoo!
Microformats – basic, simplest form of structured data
Microdata – next generation including HTML5
RDFa – most functionality, works with all XML-based languages
JSON-LD – extract and store data from all of the above . . . ." (read more at link above)