In addition to backing up preferences and related files, Back up user prefs can also restore your system using either of the two sets of previously-saved preferences, provided that two sets exist within the user's Backup_preferences folder. This feature is a very important one, since it can save the user the hours of agony required by a full system reinstallation by replacing the corrupted files that are usually the cause of serious system failures. Also, this replacement is selective: you do not have to restore everything, but can instead select, for example, only the ~/Library/Preferences folder, the browser files, the ~/Library/Mail files, etc. (see the list below). Beginning with v 2.4.8, Back up user prefs added a feature called "Auto-pilot" which enables the experienced user of the application to eliminate nearly all dialog boxes except those that are absolutely necessary for the proper operation of the application.