The TARDIS (an acronym for Time And Relative Dimensions In Space) is the time machine that the Doctor and other Time Lords travel in; it is the main vehicle for the series, which takes us to any number of times and places. It's "dimensionally transcendental"—bigger inside than out—and, in the Doctor's case, it sometimes doesn't work properly. The Doctor's TARDIS is generally stuck in the shape of a Police Call Box, a familiar shape in England in 1963 but now obsolete. The version of the TARDIS that the Doctor uses is known as a "type 39", (though the Doctor usually refers to it as a "type 40") as with the British Police Call Box, the type 39 is considered an obsolete and outdated version of a TARDIS. On numerous occasions the Doctor has attempted to repair his ship, with humorous and disastrous results. There is evidently some sort of telepathic link between the Doctor and his ship; they share a symbiotic relationship, and, as in the New Adventures, when the TARDIS malfunctions, so does the Doctor. The TARDIS is perhaps the second-most important character in the series; it is our "passport to adventure", and, in many ways, is the Doctor himself.

the reason why the TARDIS was stuck in the form of a police box was because the "chameleon circuit" in it did not work, this circuit allows it to materialize into something so it will blend in with the new environment its about to appear in, ie: if it were to land in a forest it would appear in the form of a tree or a large rock. the 6th doctor managed to finally repair the faulty circuit though he obviously decided to stick with the traditional police public call box appearance and frankly i'm glad he did!

it is a living ship and the last of its kind... her actual name is time and relative dimensions in space

That be a time machine right? From Doctor Who. Time and Relative Dimensions in Space, or something like that.

The TARDIS (an acronym for Time And Relative Dimensions In Space) is the time machine that the Doctor and other Time Lords travel in; it is the main vehicle for the series, which takes us to any number of times and places. It's "dimensionally transcendental"�bigger inside than out�and, in the Doctor's case, it sometimes doesn't work properly. The Doctor's TARDIS is generally stuck in the shape of a Police Call Box, a familiar shape in England in 1963 but now obsolete. The version of the TARDIS that the Doctor uses is known as a "type 39", (though the Doctor usually refers to it as a "type 40") as with the British Police Call Box, the type 39 is considered an obsolete and outdated version of a TARDIS. On numerous occasions the Doctor has attempted to repair his ship, with humorous and disastrous results. There is evidently some sort of telepathic link between the Doctor and his ship; they share a symbiotic relationship, and, as in the New Adventures, when the TARDIS malfunctions, so does the Doctor. The TARDIS is perhaps the second-most important character in the series; it is our "passport to adventure", and, in many ways, is the Doctor himself. http://www.answerbag.com/q_view/5816