Safe mode boot option was first introduced in Microsoft Windows 95 and is available in all versions of Microsoft Windows except Microsoft Windows 3.x, Windows NT 3.0, and Windows NT 4.0.
If the system does not start in the normal mode then it might be able to start in safe mode. This is a diagnostic mode used to start Windows using basic configuration, minimal services and generic drivers so that system errors can possibly be rectified. You can make any necessary configuration changes, and then restart Windows normally.
When the system successfully boots to the safe mode without any errors, the default settings and the basic device drivers can be eliminated as possible causes for an error.
Safe mode can also be used to back up files and data that are subject to loss due to eminent hardware failure.
