Sleep states allow the computer to enter low-power modes after a period of inactivity. The S3 sleep state is the default ...

Sleep states allow the computer to enter low-power modes after a period of inactivity.  The S3 sleep state is the default sleep state for Windows platforms.  The S3 sleep state consumes only enough power to preserve memory contents and allow the computer to resume working quickly.  Very few platforms support the S1 or S2 Sleep states.