All computing systems are state machines, and a reboot may be the only method to return to a designated zero-state from an unintended, locked state.
Minimally, some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM. The process of returning a computer from a state of sleep (suspension) does not involve booting however, restoring it from a state of hibernation does. Booting is complete when the operative runtime system, typically the operating system and some applications, is attained. Both hard and soft booting can be initiated by hardware such as a button press or by a software command. On some systems, a soft boot may optionally clear RAM to zero. after electrical power to the CPU is switched from off to on, or 'soft', where the power is not cut. Restarting a computer also is called rebooting, which can be 'hard', e.g. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some process must load software into memory before it can be executed. It can be initiated by hardware such as a button press, or by a software command. In computing, booting is the process of starting a computer.
