Firefox is killing off the Aurora release channel, which will improve the speed at which new features can be rolled out—hopefully by as much as six to eight weeks. As of April 18, there are now just three main stages for new Firefox features: Nightly (alpha), Beta (beta), and Release (stable).
For the majority of Firefox’s history (2004 to 2011) it used a conventional release cycle, with major releases roughly every year or two. With the release of Firefox 5 in June 2011, the browser moved to a new rapid release cadence that closely mirrored Google’s Chrome. Four release channels were created—Nightly, Aurora, Beta, and Release—with the Firefox code moving between each channel every six to eight weeks.
In practice, though, in the words of an unknown person at Mozilla, Aurora’s “original intent never materialised.” This is most likely because Aurora never attracted enough users to be useful—bleeding edgers went for Nightly, and the less-hardened developers and IT types went for Beta.
[Source]
