Firefox increasing rate since Firefox 1.0 was released on November 9, 2004, and Firefox had already been downloaded over one billion times. This number does not include downloads using software updates or those from third-party websites. They do not represent a user count, as one download may be installed on many machines, one person may download the software multiple times, or the software may be obtained from a third-party. In July 2010, IBM asked all employees (about 400,000) to use Firefox as their default browser. Firefox was the second-most used web browser until November 2011, when Google Chrome surpassed it. According
JavaScript differences between the various browsers (particularly within the DOM), it is useful to have access to a debugger for each of the browsers that a Web application targets. Script debuggers are integrated within Internet Explorer, Firefox, Safari, Google Chrome, Opera and Node.js. In addition to the native Internet Explorer Developer Tools, three debuggers are available for Internet Explorer: Microsoft Visual Studio is the richest of the three, closely followed by Microsoft Script Editor (a component of Microsoft Office), and finally the free Microsoft Script Debugger that is far more basic than the other two. The free Microsoft Visual Web Developer