Casing

A Dalek's casing was the shell which contained a Kaled mutant. (TV: Doomsday, TV: Resolution)

Travel machine
The Dalek casing, originally called "Mark III travel machine", (TV: Genesis of the Daleks) could be separated into three sections. The top was the Daleks' means of vision and communication, a dome with a set of twin speaker 'lights' (referred to as luminosity dischargers) (PROSE: Prisoner of the Daleks) on the upper part of the sides, and a periscope-like eyestalk in the middle. This was attached to the midsection by a "neck".

On the Dalek's midsection, the gunstick and manipulator arm were attached. These provided the Dalek's means of offence and operating capabilities. In later models, the midsection was capable of swiveling. Most of the mass of the Dalek mutant was located inside the midsection.

The bottom was the Dalek's means of mobility, consisting of a sturdy base with a skirt-like structure of plates studded with globes. This allowed movement and, in later models, flight.

The interdependence of biological and mechanical components made the Daleks a type of cyborg. The Imperial Daleks created by Davros during the Imperial-Renegade Dalek Civil War were true cyborgs, surgically connected to their shells. (TV: Remembrance of the Daleks)

Externally, the Daleks resembled human-sized peppershakers, with a single mechanical eyestalk in a rotating dome, a gunstick and a manipulator arm. The casings were made of both polycarbide and dalekanium. (WC: )

The lower portion of the casing was studded with fifty-six partially-embedded spherical protrusions, (TV: Dalek) or sense globes, (COMIC: City of the Daleks) which could serve as a self-destruct system. (TV: Dalek)

The casing was booby-trapped; when someone touched the Dalek in Utah they combusted into flames. (TV: Dalek) Even dead Daleks could prove a dangerous foe. They were frequently equipped with virus transmitters on the casing, which worked automatically. (PROSE: I Am a Dalek)

The Dalek's eyepiece was its most vulnerable spot – as there was no back-up system if this was obscured, damaged or destroyed – and impairing its vision often led to the Dalek panicking and firing its main weapon indiscriminately in a panic. (GAME: City of the Daleks) The Dalek casing also functioned as a fully-sealed environment suit, allowing travel through the vacuum of space or underwater without the need for additional life-support equipment. (TV: The Dalek Invasion of Earth, The Parting of the Ways, COMIC: The Dalek Project) A Dalek's eyepiece could be connected to other Dalek vision centres. (GAME: City of the Daleks, TV: Asylum of the Daleks)

A Dalek was connected to its casing through a positronic link. The mutant itself accessed nutrient feeders and control mechanisms inside its internal chamber. (AUDIO: The Time of the Daleks) The Twelfth Doctor once said that a Dalek was "not a machine", but "a perfect analogue of a living being". (TV: Into the Dalek) Indeed, a Dalek could be "hurt" even when the non-biological part of it was attacked. (TV: Dalek, Into the Dalek)

Due to their gliding motion, earlier models of Dalek were baffled by stairs, which made them easy to overcome under the right circumstances. One time the Fourth Doctor and his companions escaped from Dalek pursuers by climbing into a ceiling duct. The Doctor even taunted a single Dalek before disappearing. (TV: Destiny of the Daleks) Some models were able to hover, or fly under their own power like small spacecraft and travel up the stairs, ending the original weakness. (TV: Revelation of the Daleks, Dalek, Resolution, et al.)

The armour of the Cult of Skaro had temporal shift capacity, seemingly the only users of such technology during the Battle of Canary Wharf. (TV: Doomsday, Daleks in Manhattan)

Power sources
The power source of the Dalek casing also changed several times. During his first encounter with them on Skaro, the First Doctor learned that the casing was externally powered by static electricity transmitted through the metal floors of the Dalek City. Isolating a Dalek from the floor using a non-conductive material shut down the casing, although it was not immediately fatal to the occupant. (TV: "The Escape") The Daleks initially overcame this weakness by adding dishes to their casing to receive power, (TV: The Dalek Invasion of Earth) although even these were ultimately replaced by vertical rectangular slats around the midsection which absorbed other sources of power. (TV: The Chase)

Even quite late into their history, some Daleks originating on Skaro itself remained powered by static electricity: this was the case with the Daleks from the ship that crashed on Vulcan, (TV: The Power of the Daleks) although their home time postdated the Imperial-Renegade Dalek Civil War. (PROSE: War of the Daleks) Even Daleks who did not visibly draw their power supply from static electricity retained some sort of association with it, as it was by involving static electricity in his experimental time machine that Theodore Maxtible accidentally summoned into his home Daleks who nevertheless could move freely along its wooden floors. (TV: The Evil of the Daleks)

By the beginning of the Last Great Time War, the Daleks had adapted their technology to use a type of energy apparently linked to the process of time travel. On more than one occasion, Daleks and their devices were seen to leech this energy from time-travellers in order to power themselves. (TV: Dalek, Doomsday)

Whatever the power source the Daleks used in the interim, it was (apparently uniquely) immune to being drained by the Great City of the Exxilons. Strangely, the Daleks retained motive power and the ability to speak even though their weaponry was shut down, which suggests the weapon systems had a separate power supply. The Third Doctor indicated that this was because the Daleks were psychokinetic and moved around through the power of thought alone, and the City was unable to absorb psychic energy. Other references to the Daleks having psychic potential are scarce, but on the planet Kyrol, the Eighth Doctor discovered an enclave of humanised Daleks who had, through years of meditation, developed psychokinesis to a remarkable degree. (TV: Death to the Daleks, COMIC: Children of the Revolution)

Additionally, Daleks from the Last Great Time War era were surrounded by force fields that prevented bullets and energy weapons from making contact with their casings. (TV: Dalek, The Parting of the Ways, Doomsday, Daleks in Manhattan, The Big Bang)

Speech
According to certain accounts, the Dalek creature had no visible vocal apparatus as such and their voices were electronic, as the mutant inside could barely utter a squeak. (TV: Resurrection of the Daleks, AUDIO: Jubilee) In contradiction to these accounts, Daleks stripped of their casings were heard to speak in the familiar Dalek voice on several occasions, including but not limited to Dalek Caan after his casing had been ruined by exposure to the whole of time and space, (TV: Journey's End) a Black Dalek whose shell had been entirely consumed by the Kiseibya, (AUDIO: Enemy of the Daleks) and a stranded Dalek reconnaissance scout who reached Earth in the 9th century and was stripped of its casing by human warriors. (TV: Resolution) One incident showed that a human voice spoken from within a Dalek casing would gain the typical Dalek voice's metallic quality. (TV: The Daleks)

At any rate, Daleks spoke in high-pitched, stilted, robotic voices that were easy for others to mimic; (TV: The Evil of the Daleks, Dalek et al.) their most infamous battle-cry was "EX-TER-MINATE!", each syllable screeched in a frantic-sounding, electronic scream (the last two syllables together). Other common utterances included "I (or "WE") OBEY!" to any command from a superior. (TV: Destiny of the Daleks, Dalek, The Parting of the Ways et al.) Daleks also had communicators built into their shells to emit an alarm to summon other Daleks if the casing was opened from outside. (TV: Planet of the Daleks)

At one point in history the communication devices limited Dalek speech. Attempts to state their identity emerged as "I am a Dalek" and emotional statements or "you are different from me" came out as "Exterminate". Saying "I am your friend" came out as "I am your enemy". (TV: The Witch's Familiar) However, these speech restrictions were not present in earlier Daleks, who were able to speak of concepts such as friendship, mercy and servitude, often to affect cunning deceptions, set traps and manipulate others to their will (TV: The Daleks, The Power of the Daleks, The Evil of the Daleks, Dalek, Victory of the Daleks) or on rare occasions when genuinely begging for other beings' mercy. (TV: Dalek, AUDIO: Enemy of the Daleks)