You may think that you have a great handle on the use of those old meta tags. But unlike meta messages, these tags are actually a literal beast. They can only deliver what you enable them to. The article below will definitely help you to get a grasp using them the right way. And for the rest of you; consider it a refresher course.
Your title tag provides the caption, your keywords tag provide the scope of the information (and are invisible to humans), and your meta description tag provides the description – together, they form the ultra-important ‘hook’ of your advertising in the search engines, and are really the only meta-tags you need at this time, and most search engines at least look at them. Source: Accessibility 101
[tags]search engine,advertising,metatags,title tag,accessibility[/tags]