Firefox is a Web browser that is smaller, faster, and in some ways more secure than the Mozilla browser from which much of its code was originally derived. Compared to Internet Explorer, the most popular Web browser, Firefox gives users a cleaner interface and faster download speeds. As of November 2008, Firefox had about 20% of the market share for browsers, worldwide. Internet Explorer had about 70%.
Firefox includes most of the features with which users of other browsers are familiar. The first iteration of the browser also included several new features other browsers did not have at the time, such as a bookmarks toolbar and tabbed browsing that allow a user to quickly switch back and forth between several Web sites. Other browsers have since adopted many of these features, though Firefox's substantial developer base continues to create new plug-ins that offer increased usability and functionality. Because scripting controls such as Java and ActiveX can easily be unselected during installation, there is the possibility of better security.