Reformatting a computer wipes the data stored on its hard drive, allowing for a clean installation of the system and programs. (In fact, you are technically reformatting the hard drive, so ...
In 1995 my dad finally gave in to my demands and bought a Packard Bell 60mhz desktop computer. I knew nothing about computers, and as the story goes for first time users, I completely messed something ...
For businesses, reformatting a computer's hard drive is often a necessary evil; viruses and spyware, for example, can devastate the operating system and the only option left is to start over fresh.