Booting

In computing, booting (also known as booting up) is the initial set of operations that a computer system performs when electrical power is switched on. The process begins when a computer is turned on for the first time or is re-energized after being turned off, and ends when the computer is ready to perform its normal operations. On modern general purpose computers, this can take tens of seconds and typically involves performing a power-on self-test, locating and initializing peripheral devices, and then finding, loading and starting an operating system. Many computer systems also allow these operations to be initiated by a software command without cycling power, in what is known as a soft reboot, though some of the initial operations might be skipped on a soft reboot. A boot loader is a computer program that loads the main operating system or runtime environment for the computer after completion of the self-tests.