In Google search engine technology a snippet is the small sample of content shown to users on the Google search results page. In May 2009, Google introduced Rich Snippets, which according to Google is "a new presentation of snippets that applies Google's algorithms to highlight structured data embedded in Web pages".
Rich Snippets are used by Webmasters and site authors to provide a convenient summary about the search result. To display Rich Snippets, Google looks for markup formats (microformats and RDFa) that Webmasters can add to Web pages to make structured data available for Google's search results. [Source: Adapted from Google Webmaster Central]