A time capsule is a historic cache of goos and/or information, usually intended as a method of communication with people in the future. Time capsules are sometimes created and buried during celebrations such as a World Fair, cornerstone laying for a building or other event. They can also be unintended caches such as at Pompeii. The phrase "time capsule" has been in use since about 1937, but the idea is as old as the earliest human civilizations in Mesopotamia.