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. The major search engines have taken this a step further, and now use this markup to present richer search results, enabling users to more easily find the information they are looking for.
Rich snippets are snippets that have a higher click-through rate. If the click-through rate of a snippet increases, you’ll get more traffic from that search result. In the long run, rich snippets will have an effect on your ranking as well. Rich snippets also reduce bounce rates because visitors have a better idea of the page's content.