Forum Moderators: Robert Charlton & goodroi
JSON-LD is the newest and simplest markup format: it lets you embed a block of JSON data inside a script tag anywhere in the HTML. Since the data does not have to be interleaved with the user-visible text, it's much easier to express nested data items (say, the Country of a PostalAddress of a MusicVenue of an Event). Also, Google can read JSON-LD data even when it is dynamically injected into the page's contents, such as by Javascript code or embedded "widgets".
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, and Event 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.