The description meta tag remains one of the most important "behind-the-scenes" aspects of a website.
A website visitor doesn't see it when he views a page. For that reason, Google gives it little importance in determining search engine rankings.
However, when a description tag is present on a page, Google will normally use it for the "snippet" of your listing - the two lines that follow the title line - on a search engine results page.
Your page title usually becomes the lead line - call it the headline - of your listing. It either grabs someone's attention and resonates or it doesn't.
Think of the snippet then as the body of an ad. THIS is your opportunity to tell the searcher who you are and what you do.
And it is almost completely under your control.
If you aren't paying attention to this, you are missing a hugely important aspect of your Internet marketing.
If you hire an SEO company and they don't test and edit description meta tags, well then, they are skipping a factor that could easily double or triple the amount of traffic to your site.