The Aurora builds are for testing code for future Firefox version. The Nightly builds (currently Firefox 12) always get the latest changes and patches first and such changes bubble down to other Firefox versions with a delay of about six weeks, first to the Aurora channel (currently Firefox 11) and then another 6 weeks later to the Beta channel (currently Firefox 10) that then gets the next release (Beta goes to release at the end of January). Normal users should always stay on the release channel. ---- *http://www.mozilla.org/en-US/firefox/channel/ * http://kb.mozillazine.org/Testing_pre-release_versions