Mozilla's Firefox browser is unquestionably one of the most popular web browsers on the market — topping 20% at times while the browser-to-beat continues to slide — and certainly so among Open Source users. The release of Firefox 3 in June was a major milestone for Mozilla, but still, nearly six months later, there are those who have eschewed the new for the comfortable, homey, well-worn-in welcomeness of Firefox 2. That will be changing soon, though, as funeral arrangements for the second-era Fox are in full-tilt at Mozilla HQ, and the service is fast approaching.

Every Open Source project has its own unique way of replacing the old with the new. Larger projects often maintain parallel releases in active development, while many small projects move from one version to another without maintaining legacy support. Some projects support their legacies for a definite period — Ubuntu is a prime example, supporting each standard release for 18 months, and providing extended support for designated Long Term Support releases — while others utilize a more relaxed approach, dropping archaic versions as the time seems right. Mozilla falls in the former camp, supporting the old version of Firefox for six months after the release of a new one.

The six months alloted to Firefox 2 are rapidly coming to a close, and if all things go as planned, will culminate somewhere near the middle of next month with the release of Version 2.0.0.19. At that point, users will no longer receive security and stability updates for the existing versions, nor will there be any further releases or new features for the 2.0 series. According to Mozilla, two-thirds of its userbase is already using Firefox 3, and despite much dissatisfaction with this and that — as well as more than a few deal-breaking bugs — no doubt much of the remainder will migrate when support ends. Still, there will surely be some who will cling to their familiar friend, and risk exploits and vulnerabilities rather than make the switch, while a small group, if they haven't done so already, will likely opt to change browsers entirely.

It won't, however, be Firefox 2 alone that ends development in December — with the retirement of the 2.0 codebase, Mozilla is also ending further development of Gecko 1.8, the layout engine utilized in the 2.0 series of both Firefox and Thunderbird, as well as the current releases of both SeaMonkey and Camino. Asked what impact the end of 1.8 development would have on these other projects, Mozilla's Mike Beltzner responded "The end of support for Firefox 2.0 doesn't mean that [developers] won't be able to work on the Gecko code. It just means that our focus won't be on actively maintaining that [1.8] branch [of Gecko]."

For now, the only outward indication at Mozilla that anything is happening at all is a brief note on the "all older" page: "Firefox 2.0.0.x will be maintained with security and stability updates until mid-December, 2008. All users are strongly encouraged to upgrade to Firefox 3."