The TARDIS (Time And Relative Dimensions In Space) is the Doctor's primary form of transport on his countless advantures in time and space.
The Doctor's TARDIS chose him to escape Gallifrey, however the Doctor believed he had in fact stole the TARDIS, not the other way around. The TARDIS is known to be an older model, the "Type 40" TARDIS' having ceased production by the Doctor's fourth incarnation.
TARDIS "incarnations" created by the users of the Doctor Who Series.Photon Saga, the TARDIS goes through a change of appearance to fit with the "dark, tech-based" theme of the series. The console room is significantly darker than other incarnations, similar to the Eigth Doctor's. The control panels are touchscreens, and light up when a being steps onto the platform.
The TARDIS went through a complete reconstruction, with all the corridors, libraries, swimming pools and other facilities changing, including the engine of the TARDIS itself, which became much more sophisticated and effective.