For years most people have been changing and tweaking their Meta Tags on their web sites thinking that they are an important element in the ranking within Google. Many SEO companies spend a lot of time spinning their wheels and trying to convince clients that spending hours creating and editing the Tags on every page is somehow worth the time and money spent. Most SEO companies will not tell you this because they like to spend a lot of time messing with meta tags to make it look like they are doing important things for you.
But the truth is that Google does NOT use the keyword or description tags in their rankings. The only tag that is important to ranking is the Title tag - as that is the title of the web page and is used at the top.
Here it is posted on Google's own WebMaster Blog:
Two sections worthy of note:
Near the top of the page: "Google doesn't use the "keywords" meta tag in our web search ranking."
And toward the bottom of the page: "Even though we sometimes use the description meta tag for the snippets we show, we still don't use the description meta tag in our ranking."