What may be the browser's greatest strength, though, is not its feature set as much as its massive ecosystem of free add-ons -- thousands of them, in every category imaginable. That, even more than the browser itself, is what sets it apart from its competitors.
As with Internet Explorer, Firefox has all the features you want in a modern browser. There's anti-phishing, a pop-up killer, very good cookie handling, private browsing (a.k.a. "porn mode," which allows you to surf the Internet without leaving behind any trace of the sites that you have visited), excellent tab handling and more.
Firefox doesn't have much of a built-in RSS reader; its Live Bookmarks feature for handling RSS feeds is not particularly usable. However, add-ons solve the problem -- look for the excellent RSS reader called Sage.
What's most impressive about Firefox's features is not so much as what is there -- it offers fairly standard fare for browsers these days -- as the depth of those features and how they can be customized. Here's just one example: When clearing your browsing history and traces, you get control over which elements you want to clear, including your browsing and search history, form and search history, cookies, cache, site preferences and logons. And you can clear them based on time: all of them, those you've visited today, or those you've visited in the last four hours, two hours or one hour.
The anti-phishing filter, like that in Internet Explorer 8, protects not only against phishing attacks but also warns you away from sites known to attack your PC. There's also a built-in spell checker.
Firefox also offers multimedia support (by supporting the HTML 5 audio and video elements) that lets you watch video and listen to music directly in a Web page without having to launch any plug-ins. The video is displayed by Firefox itself, and includes audio and video controls. You can also download the video and audio and save it on your PC. There's a catch, though: The Web page has to use HTML 5, and few do right now. So it may or may not become important in the future.
Interface and extras