Restoring a computer system to an earlier date helps to fix unpredictable system behavior. This often occurs after the installation of new drivers and programs. Restoring the system to an earlier date allows the system to function as it did before the problems occurred.

The name of this tool on the Microsoft Windows operating system is System Restore. System Restore allows a computer to function as it did at a point in time that is in the past. Restore points are regularly created and saved on a computer. They are also created and saved manually. Restoring a system to an earlier point in time reverses system changes without deleting emails, photographs and other personal files. Although System Restore does not delete personal files, it does delete new programs, program installs and.exe files.

Apple Mac computers have a similar tool available, named Time Machine, for the OS X system. Time Machine keeps a copy of all files and creates hourly, daily and monthly backups. Old backups are deleted when the given drive reaches capacity. Time Machine is a built-in feature of OS X and can complete backups to external hard drives and an OS X Server on a given computer's network.