How do you use sleep mode?

Answer 1

When you tap the sleep key, the computer goes into a low power standby mode. Tapping the wake key brings the computer back up to a ready state. It is used instead of shutting down the computer because it is a faster way to get the computer up and running. Also, if you have a program running, there is no need to shut that off as it will be ready for you, where you left off when the computer wakes up. It is very similar to the 'hibernate' feature of many computers. Both sleep and hibernate are low power standby modes.

I never use sleep mode because I see no advantage to being able to start up my PC that much faster than if I had just shut it down.