The TARDIS, which stands for Time And Relative Dimension In Space, is a time machine and spacecraft from the British television series Doctor Who. It is famously known for its exterior appearance, resembling a blue British police box from the 1960s, but it is much larger on the inside. The TARDIS allows its pilot, often the Doctor, to travel through time and space, visiting various planets and historical periods. The TARDIS is equipped with advanced technology, including a chameleon circuit that is supposed to change its appearance to blend in with its surroundings, although it often malfunctions. It is also sentient, meaning it can interact with its pilot and has its own consciousness. The TARDIS is a central element of the Doctor Who series, symbolizing adventure and exploration.