TARDIS

The TARDIS is the Doctor's Marvellous Machine, which he uses to travel in time. It is bigger on the inside and uses the guise of a simple wooden Police Box, but in reality it is a sprawling complex of rooms, passageways and laboratories.

It was created by the Time Lords and stolen by the Doctor as a form of Trolling them.

TARDIS stands for Time And Relative Dimensions In Space, and the TARDIS has many powers over just time travel. It can travel through space as well, and can be used to get anywhere from anywhere, which is useful for the Doctor as trouble tends to follow him everywhere.