Addons are little community-created packages that give added functionality to the browser, such as add blocking, music players, debugging info, download management, chat programs, and runescape helpers (teehee) Firefox is much faster than IE, much more standards compliant (It renders webpages the way they're supposed to be rendered), it's a helluva lot more secure than IE, and it has spellcheck. :P Seriously, if you've never tried it out, I'd recommend it. Like all new things it'd take some getting used to, but once you do, it's awesome.