Google and other major search engines support the schema.org vocabulary for structured data. This vocabulary defines a standard set of type names and property names, for example, http://schema.org/MusicEvent indicates a concert performance, with startDate and and location properties to specify the concert's key details.
Data in the schema.org vocabulary may be embedded in an HTML page using any of three alternative formats: microdata, RDFa, and JSON-LD.
JSON-LD is the newest and simplest markup format: it lets you embed a block of JSON data inside a
Google is in the process of adding JSON-LD support to more markup-powered features. So far, JSON-LD is supported for all Knowledge Graph features, sitelink search boxes, Event Rich Snippets, and Recipe Rich Snippets; Google recommends the use of JSON-LD for those features. For the remaining Rich Snippets types and breadcrumbs, Google recommends the use of microdata or RDFa.