The open-source Firefox browser has now been downloaded more than 100 million times since its launch almost a year ago.
The Mozilla Foundation, which develops the browser, said the milestone was reached earlier this week. Firefox is now the second most popular browser after Microsoft’s dominant Internet Explorer.
Industry estimates give Firefox around 8% of the browser market, with Internet Explorer accounting for more than 85%.
Firefox was launched in part as a more secure alternative to Internet Explorer, but security software company Symantec recently claimed the browser was the subject of more reported security vulnerabilities than Internet Explorer in the first half of 2005.
But Mozilla says the open-source nature of Firefox allows threats to be addressed much more quickly than with Internet Explorer, with a wider community of developers moving to fix holes.
Many Firefox users also point to better features in the browser to justify their switch from Internet Explorer and other alternatives.
Microsoft will next year launch Internet Explorer 7, which is designed to be more secure against threats such as phishing and spyware. Firefox 1.5 will be launched next month.