In computing, to reboot a machine means to restart a running computer system, either deliberately or unintentionally. Rebooting can be of different types depending on the purpose for which and the manner in which it is done. It can be a cold reboot, also known as a hard reboot. This is where the power of the computing system is turned off physically and then switched on again. This causes the system to restart.
Another is the warm or soft rebooting where the system restarts on its own without the requirement of interrupting power supply. It is important to understand that the term restart refers to a reboot in a case where the operating system shuts down all programs and finalizes pending input and output operation before a rebooting process can be initiated.
Rebooting can be deliberately initiated for several reasons.It could be for the purpose of troubleshooting. Sometimes, changing operating systems could also be one of the reasons for initiating this procedure. Often times the process could be initiated by an abrupt power failure. Rebooting can also be a random procedure where the system simply crashes and causes restart.
Modern computing systems also support a process called hibernation where the system switches off temporarily and can be switched back on without having to shut off the systems entirely.