Firefox users need to regularly back up to guard against the possibility that their profile gets corrupted or wiped after installing a new extension or a new version of Firefox.
If you use Thunderbird then it’s even more important that you backup to ensure you don’t accidentally lose your email correspondence and account settings.
There are two ways to backup: use a backup utility or do it yourself manually.
MozBackup is a free utility written by Pavel Cvrcek that will automatically backup Firefox and Thunderbird as well as Netscape and the full Mozilla suite. It works like a charm – the whole process is driven by a Wizard so easy to use that even raw beginners will be able to set up automatic backups. It also offers encryption of the backup files and a complete push-button restore option.