If you are not going to use your computer for a few hours, it is a good idea to put it to sleep (also known as standby mode) to save power. If you are not going to use the computer for more than a day, it is usually best to turn it off. However, some Windows computer offer an option that combines the benefits of sleep mode and powering down the computer, called "Hibernate."
When you select Hibernate, the computer saves the current state of the system from the computer's RAM to the hard disk, then shuts down. When the computer is restarted, instead of going through the typical boot sequence, the previously saved state is automatically loaded into the RAM. The open windows and running programs from your previous session appear just as they were when the computer entered Hibernate mode. Basically, Hibernate mode acts like Standby mode, except the computer can be completely turned off. This is especially helpful for laptop computers, which will slowly lose their battery charge if they are left in sleep mode.
To make your computer hibernate, select "Turn Off Computer" from the bottom of the Windows Start Menu. Then press and hold the Shift key when the dialog box appears. The "Standby" option should change to "Hibernate." If the Standby option does not change, you may need to enable Hibernate mode in Windows. This can be done by opening the "Power Options" control panel, clicking the Hibernate tab, and checking the box that says, "Enable hibernation."