The TARDIS (Time And Relative Dimension(s) In Space) is a fictional time machine and spacecraft in the BBC science fiction television programme Doctor Who. A product of Time Lord technology, a properly piloted and working TARDIS is capable of transporting its occupants to any point in space and time. Its interior exists in multidimensional space, leading to it being significantly larger on the inside than it appears from outside. Externally, the TARDIS resembles the shape of a 1950s British police box, and the programme has become so much a part of British popular culture that the shape of the police box is now more immediately associated with the TARDIS than its original real-world function. The word has also entered popular usage and is used to describe anything that seems bigger on the inside than on the outside.