A properly optimized Meta description will enable a search engine user to determine whether your site is worth investigating in their search for the answer to whatever information they seek. In other words, meta tags become your on SERP (search engine results page) marketing tag line which is your chance to tell potential visitors to come and see your site. Very important!!
According to Wikipedia, “Meta Elements are tags used in HTML or XHTML documents to provide structured metadata about a Web page. They are part of a web page’s head section. Multiple Meta elements with different attributes can be used on the same page. Meta elements can be used to specify page description, keywords and any other metadata not provided through the other head elements and attributes.”