Originally published at: http://www.howtogeek.com/169080/beginner-geek-everything-you-need-to-know-about-browser-extensions/
Browser extensions extend your web browser with additional features, modify web pages, and integrate your browser with the other services you use. This guide will introduce you to the world of browser extensions and help you get started.
Extensions are one of the reasons power users prefer Firefox.
You mean that people use extensions other than AdBlock and WOT?