The Mozilla Foundation on Friday marked the 1 billionth download of Firefox. The feat was accomplished roughly four and a half years after the first pre-release version shipped in November 2004 and makes it one of the most popular browsers after Internet Explorer. It's commonly credited for unseating the Microsoft browser's near-absolute control of web browsers after the decline of Netscape and, as of the milestone, currently has just over 30 percent of the market while Internet Explorer has just over 60 percent.

Firefox was originally developed as a faster, leaner alternative to the now discontinued Mozilla browser. While not the first browser to implement key features like tabbed browsing, it has often been one of the first to adopt new and eventually more widespread features like quick on-page search and anti-phishing detection.

By comparison, Apple's Safari reached 11 million downloads in three days but is believed to have partly accomplished the feat through automated updates.