TARDIS

The TARDIS is The Doctor's main method of transportation in Doctor Who. The TARDIS is a Time Machine that allows its owner to travel through time and space. The Tardis was also able to change and take on a form until staying in the form of a 1963 Police Public Call Box, staying that way ever since. The word TARDIS stands for Time And Relative Dimensions In Space.

Trivia

 * The Tardis is the only machine that can take people through time and space without any negative effects.