Tardis
The TARDIS is a fictional time machine and spacecraft in the British science fiction television programme Doctor Who. The name is an acronym of Time And Relative Dimension (or Dimensions) In Space. more...
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.
In the series, the Doctor pilots a Type 40 TARDIS. Although TARDIS is the name of a class of vessel, rather than a specific craft, the Doctor's TARDIS is usually referred to as the TARDIS or, in some of the earlier serials, just as "the Ship". (In the two 1960s Dalek films, unlike the television series, the craft was referred to as Tardis, without the definite article.)
Externally, the TARDIS resembles the shape of a 1950s British police box (a special phone booth for police communications), 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.
As an acronym, TARDIS is correctly written in upper case, but there are many examples of the form Tardis in media and licensed publications. In the 2005 series episode World War Three, the caller ID of the TARDIS is displayed on Rose's Nokia 3200 mobile phone as "Tardis calling".
The word has also entered popular usage and is used to describe anything that seems bigger on the inside than on the outside. The name TARDIS is a registered trademark of the British Broadcasting Corporation.
Conceptual history
When Doctor Who was being developed in 1963, the production staff discussed what the Doctor's time machine would look like. Due to budgetary constraints, the concept of having it resemble a police box was settled on. This was explained in the context of the series as a disguise created by the ship's "chameleon circuit", a mechanism which is responsible for changing the outside appearance of the ship in order to fit in with its environment. It was further explained that the circuit was broken, therefore explaining why it was "stuck" in that form.
The concept of the police box disguise came from BBC staff writer Anthony Coburn, who rewrote the programme's first episode from a draft by C. E. Webber. Coburn is believed to have had the idea for the time machine's external form after spotting a real police box while walking near his office on a break from writing the episode. At the time of the series' debut in 1963, the police box was still a common fixture in British cities. With some 700 in London alone, it was a logical choice for camouflaging a time machine.
Read more at Wikipedia.org