A rich snippet is tool that Google introduced to help structure the way that a search result is displayed. It is a concept that is a little difficult for some people to get a handle on, but it is really not that bad. First, a user should understand that using rich snippets do not affect where a website appears in the search results. It affects what information is displayed as a search result.
Normal Meta data handed the search engines certain information to display in a search result. The Meta description is the small mini paragraph that appears under the title of the search result and gives the person searching a better idea of what a webpage is all about. This is generic information that will be displayed to every search user that sees the result.