Doctor Who is a British science fiction television series broadcast by the BBC since 1963. Doctor Who follows the adventures of the title character, a rogue Time Lord with somewhat unknown origins who goes by the name "the Doctor". The Doctor fled Gallifrey, the planet of the Time Lords, in a stolen TARDIS ("Time and Relative Dimension(s) in Space"), a time machine that travels by materialising into, and dematerialising out of, the time vortex. The TARDIS has a vast interior but appears smaller on the outside, and is equipped with a "chameleon circuit" intended to make the machine take on the appearance of local objects as a disguise. Due to a malfunction, the Doctor's TARDIS remains fixed as a blue British police box.