The Tardis

Tardis stands for Time and Relative Dimensions in Space. A Tardis is what a Time Lord uses to travel through time and space. Using Time-Lord Technology, it's larger on the inside, and contains all of the Doctor's living quarters (along with his current companion, if they're constantly traveling with him), and a swimming pool! The name Tardis was originally created by the Doctors granddaughter, Susan.

Features of a Tardis
Chameleon Circuit The Tardis's chameleon circuit allows the Tardis to blend in to it's surroundings, and fit in anywhere in the galaxy. The Doctor's chameleon circuit, however, broken when he was in 1960s London, where, at the time, the Tardis was disguised as a 1960s London Police Box. Because it broke, it stays as a 1960s police box no matter their place or time in the galaxy. Because of the Doctor's helping hand to anyone in need, the blue box and it's landing noise has become a beacon of hope to many people.