Desription of site

How do you get the text description you see at the bottom of sites when you Google, Yahoo etc.?
For example if you click the below link it reads “[SIZE=-1]Enables users to search the Web, Usenet, and images. Features include PageRank, caching and translation of results, and an option to find similar pages.”

[SIZE=-1] How can I get my site to read something?[/SIZE]