search engine optimization — basics
Description Meta Tag
Use the "description" Meta Tag
The description meta tag gives search engines a summary of the page's contents. While Google and other search engines now exclude meta tags from natural search result algorithms, meta tags still do serve an important purpose.
Whereas the <title> tag is a few words or a short phrase, the description meta tag may be up to a short paragraph. Google may use a portion of the description meta tag text as a search result snippet if it does a good job of matchup up with a user's search. Google will extract the portion of the text that best matches the user search. Put the best page content description within the first 166 characters.
A good, informative meta tag can drive additional traffic. In this example from Google's SEO Starter Guide the "description" meta information shows the description appearing in the search result. This informative description promotes the content.
A user searches…
…the results display an informative page title and a snippet from the description meta tag that promotes the content…
Use unique descriptions for each page if at all practical. Do not just copy and paste page content into the description meta tag. Do not "stuff" the description meta tag with keywords—keywords here will not improve your Page Rank.
While the meta tag "description" will not improve your Page Rank it is important if you want the user to select your site from the 10 returned on the page. You want to give the qualified user every reason to click the link to your page.