Extensions [also referred as add-ons or plugins] are small piece of software that add new features to Mozilla Firefox*. Themes are the same but they alter graphical interface of your favourite Internet browser, Firefox.

*Mozilla Firefox (originally known as Phoenix and briefly as Mozilla Firebird) is a free, cross-platform, graphical web browser developed by the Mozilla Foundation and hundreds of volunteers. It makes Internet browsing (surfing) faster, easier and more secure. It's open for new features / themes and this site is here to share information about Firefox extensions and plugins, to further the Firefox browser and expand the circle-of-Firefox friends.

Extensions are packed in .xpi (which can be extracted & edited with archieve software like WinRAR) and they add many usefull things to FF, from small to big one. Themes are often found in .jar format. Depending on your needs, you can update Firefox with ease - all you need to do is to find proper extension or theme, see what feature/which interface it brings and if you like it, simply click on installation link, download & install it (it will happen automatically). At the end, restart Firefox and voila, enjoy using extra features or hot design you just got.

At FFExtensions.com you can search for extension/theme by name, or browse them by category: