Hibernation (also known as suspend to disk, or Safe Sleep on Macintosh computers[1]) in computing is powering down a computer while retaining its state. When hibernation begins, the computer saves the contents of its random access memory (RAM) to a hard disk or other non-volatile storage. When the computer is turned on the RAM is restored and the computer is exactly as it was before entering hibernation. Hibernation was first implemented in 1992 and patented[2] by Compaq Computer Corporation in Houston, Texas.
Microsoft's Windows 8, Windows 8.1, Windows 10 and Windows 11 employ a type of hibernation (Fast Startup) by default when shutting down.[3]