A warm boot, accomplished by pressing the CTRL+ALT+DEL key combination, restarts the computer
This warm-boot procedure usually does not go through the complete boot process; generally, it skips the power-on self test (POST) to save time. In addition, a warm boot frequently fails to reset all adapters in the computer’s adapter slots.
A warm reboot is also known as a soft boot, warm boot or warm restart.
Reboots can be either cold (alternatively known as hard boot) where the power to the system is physically turned off and back on again, causing an initial boot of the machine, or warm (alternatively known as soft) where the system restarts without the need to interrupt the power.