If your computer crashes, you can quickly restore it to working condition using the System Restore utility in Microsoft Windows. System restore periodically creates what it calls a restore point. The restore point is a "snapshot" of the Windows Registry and selected system files. Windows also automatically creates a restore point prior to the installation of certain programs.
If a problem is detected during an installation, you can run System Restore to set things right. Pick a restore point before the problem occurred, and System Restore will then undo any changes made since the restore point was created. This will restore your system to its previous working condition.
Note, however, that because System Restore only monitors system files and Registry settings, you cannot use it to restore changed or damaged data files. For complete protection, you'll still need to back up your important data files manually.