Firefox add-on is small piece of code written by a programer or enthusiast from anywhere in the world. Add-ons can add to the capabilities and usefulness and can also enhance visual appearance of Firefox. Using add-ons, one can customize Firefox to make it more useful and visually apealing. Three broad categories of add-ons.
* Plugins*
Plugins help the Firefox browser perform specific functions like viewing some graphic formats or playing multimedia files. This includes AdobeReader, Flash player, QuickTime, Java plugins. Plugins are slightly different from extensions, which modify or add to existing functionality.
* Extensions*
Extensions add new features/ functionality to Firefox, or modify an existing one. There are extensions that allow you to block advertisements, add some useful functionality like proxy switcher, dictionries, media downloader, integrating browser with social networking sites and also and add features similar to other browsers.
* Themes*
Themes change the visual appearance of Firefox. Some themes simply change the toolbar's background colors; other themes make Firefox look like a completely different. Some themes cam make the Firefox look like Safari or InternetExplorer.