Time capsule

A time capsule may be:

Historic cache of goods and/or information

A method of communication with people in the future. Sometimes created and buried with much hoopla during some celebration such as a World Fair, cornerstone laying for a building or other event. Many times embedded in the cornerstone of a building as it is built - city hall, major sports arena, etc.

A time capsule is sometimes buried by an individual in a special place which will be dug up by a descendant.

Contents can include such things as newspapers, recordings, memorabilia

The ultimate time capsule is the Voyager Golden Record, attached to two spacecraft for the benefit of spacefarers in the distant future.

Fictional Vehicle

Vehicle which might be used (in fiction) to travel in time