Google uses three steps to rich snippets
by Google
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1. Pick a markup format.

Google suggests using microdata, but any of the three formats below are acceptable. You don't need any prior knowledge of these formats, just a basic knowledge of HTML.

Microdata (recommended)
Microformats
RDFa
2. Mark up your content.

Google supports rich snippets for these content types:

Reviews
People
Products
Businesses and organizations
Recipes
Events
Music
Google also recognizes markup for video content and uses it to improve our search results.