different Tardis's

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his is a general article on a type of vessel. For discussion of the vehicle used by the Doctor, see The Doctor's TARDIS and TARDIS A TARDIS or TT Capsule was the main kind of space-time vehicle used by the Time Lords.

A TARDIS was grown from coral, a process that could take many centuries.

Name: "TARDIS" was an acronym. Susan told Ian Chesterton and Barbara Wright that she had "made up the name 'TARDIS' from the initials" of the full name, "Time And Relative Dimension In Space".

 It was once indicated that she gave the Doctor the idea of the acronym when he was possibly the Other.

 Although some Time Lords, like Castellan Spandrell and Romana I, utilised the more generic name "TT capsule", others were perfectly familiar with Susan's supposed acronym. Some beings on the fringes of Time Lord society, like the Sisterhood of Karn, also knew the acronym without being prompted by the Doctor or his companions. There was a slight discrepancy as to the precise meaning of the acronym. Vicki pluralized the "dimension" when she explained the term to Steven, making it "Dimensions". This interpretation seemed to hold for a time, being used by several subsequent companions and Doctors.

Nevertheless, the singular Dimension, may have been "more correct", as the Doctor's fifth, eighth, ninth and tenth incarnations — as well as their respective companions — consistently preferred the original, singular form, as did the Doctor's TARDIS itself when its matrix was transplanted into Idris. The "dedication plaque" in the Doctor's TARDIS also referred to the ship as "Time and Relative Dimension in Space", favouring the singular form.

 Flight: TARDISes usually moved through time and space by "disappearing there and reappearing here" a process known as "de- and re-materialisation". This was controlled by a component called the dematerialisation circuit. They also could fly through space like conventional spacecraft, but doing so for prolonged periods could damage to the ship, at least in the case of the Doctor's TARDIS.

 During operation, a distinctive grinding and whirring sound was usually heard. River Song once demonstrated a TARDIS was capable of materialising silently, teasing the Doctor that the noise was actually caused by leaving the brakes on. Other, newer TARDISes, flown by other pilots (such as the Master and the Rani) made the same sound in the course of their normal operation; the Minyans' computer recognised the sound as associated with Time Lord ships. The Doctor himself materialised his TARDIS more than once without making the distinctive noise.

This sound was also made by other devices: SIDRATs, a craft similar to TARDISes used by the War Lords; a Time Lord who appeared to the Doctor (without using any visible means of transport) to warn him of the appearance of the Master; when the Time Lords provided the Doctor with a new dematerialisation circuit, it appeared on a table making this sound (since this was the part of the TARDIS which controlled its materialisations, it may have been operating under its own power; and when the Doctor modified Skagra's invisible spaceship to fly like a TARDIS, again, this sound was heard.

 When a TARDIS materialised, it could sometimes result in strong wind and small tremors, enough to shake wine glasses, in the area where it appeared.

 If a TARDIS materialised in a space occupied by another object, that object might appear inside the TARDIS. Once, the Doctor landed an incomplete TARDIS in his own TARDIS and on top of an Ood; the Ood was atomised. (DW: The Doctor's Wife) Conversely, a TARDIS could dematerialise while leaving its occupants behind. If a TARDIS landed in the same space and time as another TARDIS, a time ram could occur, destroying both TARDISes, their occupants and even cause a black hole that would destroy the universe. However, time rams could be avoided by materialising inside the other TARDIS. This act itself also had inherent dangers, including space loops.

Types: TARDISes were of two broad categories — exploratory and military. Of the two, TARDISes without armaments were apparently more common.

 Exploratory: Most TARDISes were used for the observation of various places and times. This kind of TARDIS underwent much modification over the years. Each new model received a distinct number to differentiate it from other models. The numerical scheme was seemingly simple; the higher the number, the later the design had been produced. However, two types of numbering schemes may have been employed. The Monk called his version a "Mark 4", and the First Doctor's reaction seemed to suggest that he had a lower-numbered model. Subsequent incarnations and other Time Lords called the Doctor's TARDIS a "Type 40". It is also possible that each type had several marks. Thus, both the Monk and the Doctor might have had "Type 40s", the Monk's a later version of a Type 40.

Whatever the case, TARDISes were generally referred to using the nomenclature Type X. For instance, the Second Doctor, while working for the Celestial Intervention Agency, was briefly assigned a Type 97 TARDIS. The fifth incarnation of the Doctor once remarked that he should have upgraded to a Type 57 TARDIS. On another occasion, he noted that a Type 70 would allow him to break through a temporal distortion grid, but that his Type 40 was not cut out for such a "brute force approach". In his eighth incarnation, he encountered the Type 103, which appeared to be a near-human.

 By the time of the Doctor's fourth life, the entire Type 40 line had been retired from use.  This policy ostensibly helped the Time Lords police time travel by reducing the total number of TT capsules in use at a given moment in time. Policing was further assisted by ensuring that individual units of the same model had the same key. Thus the Castellan's guards were able to easily affect entry into the Doctor's TARDIS. (DW: The Invasion of Time)

 Military: On more than one occasion, the Doctor encountered heavily armed battle TARDISes carrying time torpedoes, developed during his fifth incarnation or earlier.

Features and functions: Dimensionally transcendental: The TARDIS seen from the outside in. One of the key features of a TARDIS was that the interior existed in a dimension different from the exterior. The main application of this concept was that it was a different size on the inside than the out. With the exception of Iris Wildthyme and Professor Chronotis' TARDISes, this meant that they were bigger on the inside than the outside. The Fourth Doctor once explained the phenomenon by using two boxes, one smaller than the other,. He placed the larger one down and moving away from it so that the big box looked as if it could fit within the small box. He explained that if the big box could be accessed from the small box it would be bigger on the inside. Once the Time Lords realised that, it was a small feat making them bigger on the inside than the outside suggested.

 Chameleon circuit: One feature of all TARDISes was their ability to blend into their surroundings once they landed. If working properly, a chameleon circuit would assess the surroundings just before arrival and change the exterior to resemble something common to that landscape. On the one occasion he got it working after leaving London in 1963, the Doctor's chameleon circuit appeared to give him no control over the change. However, were the mechanism functioning correctly, it would have been programmable from a keyboard on the TARDIS's main console. Later models may have allowed greater flexibility. The Master's ability to produce an architectural column in sometimes incongruous environments like the Pharos Project or Heathrow, as well as the Monk's statement that he chose to make his TARDIS look like a sarcophagus perhaps indicated the circuits of later models could indeed be manually operated. This idea was further substantiated when the Doctor entered the Monk's TARDIS and changed its appearance from a pillar of stone to a police box identical to his own TARDIS. In Logopolis, it is implied that the Doctor could select what the TARDIS would look like. He even demonstrates to Adric how he would change the TARDIS into a pyramid, if the chameleon circuit were functioning properly.

Organic machines: TARDISes were incredibly complex machines. The nature of their construction was such that they were said to be grown rather than constructed, thus simulating a biological process, though it is not clear whether this is indicative of the machine being biological in nature or simply so intricate and complex as to appear to mimic the processes of a biological entity. Due to the level of complexity in their construction, TARDISes had a certain degree of sapience, and could take independent action, as when the Doctor's TARDIS resurrected Grace Holloway and Chang Lee, or when someone looked into the heart of the TARDIS.

 Conflicting evidence from many sources, such as other Time Lords and the Doctor himself, make unclear how the average TARDIS was alive, and whether that life extended beyond artificial sapience and into a biological existence. Some more-advanced TARDISes, such as Compassion, were fully sapient beings in their own right. TARDISes often "mourned" the death of their Time Lord pilots, even going so far as to commit suicide by flying into a sun or hurling themselves into the Time Vortex. The Fifth Doctor claimed there was "an elephants' graveyard" of TARDISes somewhere at the end of time.

Because the TARDIS displayed these organic traits, the Doctor considered his TARDIS to be alive. He talked to and stroked parts of the TARDIS when he operated it. He diagnosed mechanical difficulties as medical conditions like "indigestion." He once commented that a TARDIS was "more like a person." On one occasion, the Doctor's TARDIS manifested an avatar to help him fight a mental battle, taking on the forms and personas of the various companions who had ridden in it – however, this was when the Doctor was unconscious and was battling within his own mind. When Amy told him she thought him mad for talking to a time machine, the Eleventh Doctor told her that the TARDIS could, in fact, hear him. When the matrix of the Doctor's TARDIS was placed inside the body of a human female, it was learned that they were in fact sentient beings with some degree of free will. The TARDIS said in her human body, "All of my sisters are dead." This implies that all TARDISes were female.

Rassilon Imprimatur: Before a TARDIS was fully functional, it needed to be primed with the biological imprint from the symbiotic nuclei of a Time Lord's cells. Known as the Rassilon Imprimatur, this gave them a symbiotic link to their TARDISes and allowed them to survive the physical stresses of time travel. Without the Imprimatur, molecular disintegration would result — a safeguard against misuse of time travel — even if the TARDIS technology were copied. Once a time machine was properly primed, however, and the imprint stored on a component, it could be used safely by any species.

Specific TARDISes: The First Doctor stole his TARDIS. By the time of his fourth incarnation, all other Type 40s had been de-commisioned, save his. Following the events of the Last Great Time War, the Tenth Doctor believed that his was the last TARDIS in existence.

 Possessed by other renegades: The Rani prepares to enter her TARDIS.

The Master possessed at least two TARDISes. According to the Doctor, the Master's had a Mark II dematerialisation circuit. The Rani, the Monk and Iris Wildthyme also had TARDISes. Iris' may have been even older than the Doctor's.

Unique TARDISes: Compassion (a former member of the Remote) evolved into a TARDIS, the prototype of the sentient Type 102, the only one of that type. The first generation of mass produced sentient TARDISes was the Type 103.

 Lolita evolved from a type 45 TARDIS that had previously belonged to the Master.

 Idris and The Doctor also built the junk TARDIS out of dead TARDIS parts from the Bubble universe's junkyard.

 Copies of TARDIS technology: During the Doctor's second incarnation, the renegade Time Lord known as the War Chief provided similar time ships named SIDRATs to the War Lords to further their plans of conquest. When they learned of this, the Time Lords placed the War Lords' planet in a time loop. When the Skith probed the Doctor's mind they gained knowledge of the TARDIS and made their own version, the SKARDIS. When the Daleks gained time travel, they made a version of the TARDIS, the Dalek time machine. An alternate reality UNIT, under the command of Rose Tyler, used technology taken from the Doctor's dying TARDIS to create a time machine to send the alternate Donna Noble back in time to correct history. 79B Aickman Road was a copy of TARDIS technology.