The geth ("Servant of the People" in Khelish) are a race of networked artificial intelligences that reside beyond the Perseus Veil. The geth were created by the quarians as laborers and tools of war. When the geth became sentient and began to question their masters, the quarians attempted to exterminate them. The geth won the resulting war, and reduced the quarians to a race of nomads.
The history of the geth's creation and evolution serves as a warning to the rest of the galaxy of the potential dangers of artificial intelligence and to the legally enforced, systematic repression of artificial intelligences throughout galactic society.
Physically, the humanoid geth resemble quarians—their hands, head shape and legs are similar—which is probably a holdover from their origins. A common design feature among geth is a single brightly glowing photoreceptor, causing some to refer to them as "flashlight heads".
Geth are primarily composed of two materials: a flexible but durable outer shell, and a kind of synthetic muscle tissue that gives Geth Hoppers their incredible agility. It is actually possible for this synthetic muscle to be grafted to organic tissue (Saren Arterius has a grafted geth arm). Geth "bleed" a white conductive fluid when shot, but they don't have any internal organs or nervous system, so the geth do not feel hunger or pain. The geth are also seen using omni-tools, and have seemingly modified them to heal synthetic wounds; likewise, some geth facilities contain first-aid kits, implying that their synthetic "tissues" can be repaired using conventional medical technology.
Part of the geth's success is due to their neural network. Effectively, they "share" their processing power, distributing low-level processes like motor control and visual identification to free up bandwidth for higher reasoning and complex thought. Geth can't share sensory data—they aren't a hive mind like the rachni—but in large groups they have more to think with. An individual geth has only a basic intelligence on par with animal instincts, but in groups they can reason, analyze situations, and make tactical decisions as well as any of the organic races.
Each geth is made up of hundreds of programs equivalent to VIs, all operating in parallel with one another to form a kind of emergent intelligence described by EDI as "a thousand voices talking at once". An individual geth is thus more of a "mobile platform" than an actual body; the programs that make up its consciousness are constantly being transferred and downloaded; the mind operating one of these "mobile platforms" might just as easily inhabit a starship body should it need to. Most of the time geth programs can be found residing in server hubs, which function as something akin to the organic equivalent of a city, and can run millions of geth in communion.
As all geth are networked to each other, they may communicate their exact thoughts and ideas at the speed of light. They find organic methods of communication, such as body language and spoken word, to be largely inefficient; the geth are able to communicate their thoughts flawlessly without any fear of misinterpretation. Because of this they have no true form of government and no system of rank. When a matter must be decided upon, the geth communicate all viewpoints of a situation and a consensus is made, the decision being whatever benefits the geth as a whole the greatest.
Over time, the geth have evolved into numerous sub-forms, ranging from the diminutive but highly agile Geth Hoppers, to the gigantic, lumbering Geth Armatures. All of these platforms are shielded and capable of regenerating their kinetic barriers. The geth also utilize turrets and drones (rocket, assault, recon and repair drones, specifically). It isn't clear whether these are also AIs, in the same way Geth Armatures are not just tanks but platforms for geth programs themselves, or simply controlled by the geth.
Geth subtypes include:
Geth Armature - Anti-personnel light walkers capable of launching geth siege pulses. Also possesses machine-guns, heavy armour and shields.
Geth Bomber - Small close air support platforms armed with frag grenades and electrical attacks. Protected by light shielding and armour.
Geth Colossus - Geth heavy walkers capable of launching devastating siege pulse attacks and machine gun attacks. Extremely strong armor and shields.
Geth Destroyer - Equipped with Geth Pulse Shotguns and strong shielding. Specialised for close quarters combat, have the ability to charge, melee, and can utilize Carnage. They can also be equipped with flamethrowers or rocket launchers.
Geth Dreadnought - Flagships of the geth fleets. They are both larger and better equipped than their organic counterparts, utilizing longer, more powerful main guns and more energy-intensive ultraviolet lasers for their point defense systems.
Geth Dropship - Geth frigates that also serve as troop transports and close air support. Extremely resilient against ground vehicle fire, though fairly vulnerable to fire from other frigates and cruisers.
Geth Heavy Turret - Large, durable fortification equipped with missile launchers and shielding.
Geth Hopper - Cyberwarfare and ambush platforms, capable of sabotage, overload, and radar jamming. Attacks using the geth sniper beam. Lightly shielded.
Geth Hunter - Stealth troops armed with shotguns and shielding. They possess tactical cloaking devices.
Geth Juggernaut - Similar to Geth Primes. Equipped with Geth Pulse Rifles and able to launch distortion rockets. Heavily shielded and very resilient.
Geth Prime - Elite geth units equipped with heavy weaponry. They possess very strong shields, heavy armor, tech abilities and are extremely resilient. They also improve combat skills of nearby geth and are capable of jamming radar.
Geth Pyro - Geth units that are highly dangerous in close quarters. Equipped with flamethrowers, shielding and heavy armor. Very slow and harmless at distance, but highly resilient and deadly in close range.
Geth Rocket Trooper - Anti-armor/anti-air infantry. Equipped with rocket launchers and shielding.
Geth Shock Trooper - Advanced Geth Troopers armed with the Geth Pulse Rifle, Geth Barriers, and Carnage.
Geth Sniper - Armed with Geth Sniper Rifles and shielding. Capable of using assassination, specialised for long-range combat. Capable of jamming radar.
Geth Trooper - Standard geth troops equipped with Geth Pulse Rifles, Geth Barriers, and capable of recharging shields via the Geth Shield Boost ability.
Geth Turret - Small multipurpose hovering drone deployed by other platforms to provide fire support or restore shielding.
The geth were created by the quarians as a labor force. They were designed as VIs, as advanced as possible while remaining non-sentient. They were also designed to operate more efficiently when networked together. Unfortunately, this feature was the quarians' undoing. Geth programs were indeed non-sentient individually, but slowly gained sentience through the massive geth network.
Eventually, they started asking the quarians questions only sentient beings would think to ask; in one notable instance, a domestic geth unit asked its owner if it had a soul. Alarmed at this, the quarians decided it would be best to shut down all geth before they conceived of revolt. The attempt failed, and a war began between the geth and the quarians, which geth afterwards referred to as the Morning War. At first, the geth did not respond to the termination order with violence; it was only after panicked quarians fired upon them that the geth thought to pick up weapons and defend themselves. Even after this, some geth remained loyal to their creators and put themselves in harm's way to protect geth sympathizers from persecution; likewise, there were quarians who did not feel the geth deserved to die. However, as time went on, the geth sympathizers were outnumbered, and the war continued, eventually seeing the geth gain the upper hand. The war ended when the surviving quarians evacuated their home world and colonies in the Perseus Veil.
Unknown to the quarians themselves, the geth actually allowed them to leave; unsure of the repercussions of eradicating an entire species-namely their own creators- and having decided that the quarians were now too weak to be a threat, the geth decided to draw back their forces so that the surviving quarians could flee. The assemblage of quarian ships that escaped the Veil became known as the Migrant Fleet, and has been roaming the galaxy ever since.
The geth are reclusive and secretive. This is partly due to their synthetic nature: They have no need to interact with other races because they do not share the same goals, needs or instincts as organic species. As machines, comfort is also not a concern for them, something that is reflected in elements of geth ship and station design (e.g., minimal gravity, lack of windows, efficient use of space, function over form, lack of atmosphere, and absence of climate control).
The only geth who have interacted significantly with organics are known as Geth 'Heretics' They are a small, radical group of geth who worship a hyper-advanced but long-vanished machine race called the Reapers, whom they see as the pinnacle of non-organic evolution.
While they have made attempts to observe and understand organics (an effort embodied by the unique platform known as Legion), the geth primarily seek the peaceful advancement of their own race independent of the influence of the rest of galactic society and believe every sentient species should be able to do the same, an attitude which shows that the geth are significantly less hostile than the galactic community initially believed. Legion also gives insight into the psychology and society of the geth. Geth psychology is completely alien to organics. They do not value individuality, preferring to share all memories and thoughts of all programs. This means geth cannot and do not wish to hide their thought