In computers, this operating state is supported by the power management of the operating system and serves to save energy; in mobile devices such as notebooks, tablet PCs and wireless network components, it serves to extend battery life.
If a mobile device goes into Sleep Mode, it first switches off the display, the fan and the hard disk drive. When transitioning from Sleep Mode to Active Mode, the computer resumes at its previous state.
The Sleep Mode knows different operating states like the Standby mode, the Hibernation mode and the Hibernation with the Power-Down mode. The operating states differ in the amount of power saved and how and where the currently used data and programs are stored. Sleep modes can also be combined as hybrid operating states. For example, sleep mode with hibernation.