Yes, Aurora is one of the development builds that receive an update daily and keep the same version number (31.0a2). The number only changes when the release version gets a major update and changes its version number to the next major version The next release change will be 29.0.x to 30.0 and Firefox 30.0 is currently beta, so beta then will change to 31.0 and Aurora to 32.0a2 and Nightly to 33.0a1.

• https://wiki.mozilla.org/Releases

If you do not want these daily updates then best is to stay with the current release or install the Beta version that usually updates twice a week.

You can find the full version of the current Firefox 29.0.1 release in all languages and for all Operating Systems here:

• http://www.mozilla.org/en-US/firefox/all.html
• http://www.mozilla.org/en-US/firefox/beta/all/

If the a-number doesn't really increment, what is the difference between a1 and a2?

The buildID (gecko.buildID) changes to reflect the current date that the file has been compiled. Help > About shows this date in parenthesis after the Firefox version number. Builds from the Aurora channel are alpha 2 builds (a2) and the Nightly update channel (bleeding edge) that has the latest patches are alpha 1 builds and more likely to be unstable than other development builds.

See also:

• http://kb.mozillazine.org/Testing_pre-release_versions

The Nightly development channel always have it as version X.0a1, the Aurora channel as X.0a2 and Beta as X.0bx (current Beat build is at 30.0b7 for example).

The Aurora and Nightly channel get checkins almost everyday so therefore they get a update each of those days.

Note that Aurora channel usually gets updates disabled on Monday then get enabled again on Friday of the week of the versions move/merge to next channel around time of Release. The Aurora channel tends to get a lot of last minute checkins so it can be a bit unstable when version moves from Nightly to Aurora channel.