Technically speaking, the Nightly Build is only for testing purposes and is the most unstable version of FF available. Here's a brief explanation: In order of

Technically speaking, the Nightly Build is only for testing purposes and is the most unstable version of FF available. Here's a brief explanation: In order of development - some new features may come and go from channel to channel. Nightly - Under heavy development. Least stable/secure. First tests of new changes/features; some changes/features introduced in Nightly may be removed before Release and other versions. Only for testing. Should only be used by very experienced users/testers. Aurora - Still under development. More stable/secure than Nightly. Some bugs may still be present that need resolution. Should be used by experienced users only who can post/report reproducible problems and work around issues. Beta - Final development stage before Release. Usually good stability/security. Major bugs resolved. Working out final bugs. Preview of what Release version will most likely contain in the way of changes/features, though some changes/features can still disappear before Release. Release - Final channel released to public for everyday use. https://support.mozilla.org/en-US/questions/970739 https://support.mozilla.org/en-US/questions/970739