Rich results are the enhanced blue links: star ratings on a product, an FAQ dropdown, a recipe card, a how-to carousel. Each one is unlocked by a specific schema.org type (Product, FAQPage, Recipe, HowTo, Article, etc.).
Google's preferred format is JSON-LD embedded in the <head>. Microdata and RDFa still work but are harder to maintain because they interleave with markup.
Structured data doesn't directly boost rankings, but rich results measurably raise click-through rates — often 20–30 % for FAQ and how-to snippets.