What is the main advantage of using Meta Description tag in SEO

[alex.thomson]

BENEFITS OF META TAGS
There are two reasons to use meta tags:
1. Search Engine Optimization (SEO)
2. Browser Behavior
* Search Engine Optimization
The Meta tag is a very useful tag for webmaster who wants to customize their website listings on search engines. Meta tags can also help improve placement (or ranking) of your web pages in search engines like google. But not all search engines use meta tags, some very old search engines lack the technology or features to use meta tags, a good example is Lycos.
So if you want to improve your website ranking, using meta tags, can be very useful and advantageous. so take advantages of this HTML tag.
* Browser Behavior
Browser Meta Tags define particular things about a web page, for example, what character set to use when displaying the characters on the page, or what language the HTML document is written it, or how many long should wait before refreshing the page or redirecting to another web page.