Rich snippets are a type of on page mark-up.They are the extra bits of text that appear under search results. Think of them like bacon bits for search engines. That extra pop of flavor that differentiates you from the plain old potato next to you. Are they necessary? That depends. Do you want your listing to stand out? If so,rich snippets are a great way to get your content noticed!
Benefits of Rich Snippets:
1) Attract more visitors.
2) Decrease bounce rate.
3) Help to be in the first page on search engine.
4) Help to get more traffics on your site
& many others.