The troubleshooting mode of an operating system. By pressing a particular key after the computer is turned on, it allows the system to boot with only essential components such as the OS kernel and mouse, keyboard and basic display drivers. All applications normally set to automatically launch when the computer is booted are bypassed. As long as there is no corruption of the OS on the hard disk, when the computer cannot boot due to software or hardware conflicts, it can generally boot into safe mode. While in safe mode, offending configuration data or software components can be deleted, or drivers can be manually loaded one at a time to determine which one begins to cause a problem.
Windows Safe Mode
To boot into safe mode, press and hold the F8 key right after the computer is turned on and before the Windows logo appears. See
Win Safe Mode.
Mac Safe Boot
To boot into safe mode, press and hold the Shift key after the computer is turned on.
Linux Safe Mode
Using the command line, Linux/Unix computers can be booted into various run levels that determine which resources are loaded. For example, "runlevel 1" is typically the equivalent to Windows and Mac safe modes. See
runlevel.