Customize the way a web page displays or behaves, by using small bits of JavaScript.
Greasemonkey is a Firefox add-on which will offer you the possibility to personalize the appearance and functionality of webpages.
Hundreds of scripts are already available for free. And if you're the tinkerer sort, you can also write your own.
The purpose of Greasemonkey is to manage user scripts. User scripts allow the user to control the way they use the web, by customizing it with scripting. The Greasemonkey extension won't do any good without any scripts installed.
