What is a cold boot?

A cold boot refers to the process of starting a computer that is completely powered off. This action involves turning on the computer from an off state, which means that all system components must go through the initial power-on self-test (POST) and loading of the operating system. Cold boots are distinct in that they reset all hardware and software states, ensuring the computer starts fresh.

In contrast, other options describe actions that do not involve starting the computer from a completely off state. Restarting a computer while it's on pertains to powering it down and booting it up again without it being turned off completely, which is fundamentally different from a cold boot. Waking a computer from hibernation involves bringing it out of a low-power state rather than starting it from a full shutdown. Similarly, turning off and immediately on the computer may appear similar to a cold boot but does not convey the aspect of starting from a completely powered-off condition since it implies a quick transition rather than a full initialization.