What type of booting does the computer go through when starting up from a powered down ?

Booting is the process of starting up a computer and loading its operating system into memory. The type of boot depends on the state the computer was in before it started: a warm boot or reboot happens when a computer that is already switched on is restarted, either through software or a reset button, without disconnecting its power supply.

Starting a computer from a completely powered-down state, where it had no power running through it beforehand, is called a cold boot. During a cold boot, the system must run its full startup checks from scratch, including the power-on self-test, since none of its circuits were already active.

Distinguish the two by the starting condition of the machine: powered off before starting means a cold boot, while restarting a machine that was already on means a warm boot.