The small portion of content you see under the link, when you give a search query on a search engine is what rich snippets are all about. It adds more info for the user to understand if the link is actually relevant to the user and the search query presented to the search engine. The meta description you add when you use a SEO plugin on, say, WordPress is basically what constitutes the rich snippet.

Rich Snippets is the term used to describe structured data markup that site operators can add to their existing HTML, which in turn allow search engines to better understand what information is contained on each web page.

Informative information, thanks for sharing with us.