Meta elements are tags used in HTML or XHTML documents to provide structured metadata about a Web page. <meta name="description" content="The Federal Aviation Administration is an operating mode of the U.S. Department of Transportation."> Wiki description but meta tags are keywords your website is suppose to be about. Some say they aren't important in SEO - like the Yoast guy and their bloated plugin. I try to include them just in case as you never know.
Meta tags or Meta elements are used with HTML code; these are used to give a certain type of structure called metadata to a web page. When a webmasters codes their sites they can use the tags in the head area of the HTML page.
