The human AI Cortana has a female personality and a blue avatar.

"The problem for an A.I. isn't doing a thousand things at once. It's slowing down and imparting all that information to humans. I love you all to bits, but you're something of a bottleneck in my processes." --Black Box

An Artificial Intelligence, commonly known as 'A.I.', is an artificial construct that exhibits intelligence similar, and in some categories far superior, to a sapient biological being. AI technology was used by the Forerunners and was later developed by humanity. According to the Forerunner Technological Tier ranking system, the extensive use of AI is one of the components for sociological and technological advancement. The Covenant also made use of AI technology, but only in its simplest form, as their religious doctrine forbade the creation of more sophisticated thinking machines. 

Human AIs include both "smart" and "dumb" varieties. Humanity developed the first-generation "smart" AIs in the mid-21st century. Most human AI constructs give themselves an avatar, a unique visual representation that typically reflects an aspect of the AI's personality or corresponds to its main use.


The process of creating an A.I. is different to what most people realize. Instead of simply "programming" a Smart AI the A.I. matrix is actually created by sending electric bursts through the neural pathways of a human brain which are then replicated in a superconducting nano-assemblage in a process known as Cognitive Impression Modeling. This destroys the original brain tissue, however, and so the brain being used could only be obtained after the host had died. However, in some instances, as in the case of the A.I. Cortana, the candidate brain was flash-cloned and had its memories transferred to the receptacle organs so that the host, in this case, Dr. Catherine Halsey, could remain alive. However, this is extremely inefficient. In the case of Cortana, out of twenty of Dr. Halsey's cloned brains, only two of them took.

Dr. Halsey supervised the creation of the template for every third-generation "Smart" A.I. on the planet Reach. She has extensive knowledge on how A.I.s work.

Human AI's

Creation and Design

The process of creating an AI differs depending on whether it is of the "smart" or "dumb" variety. "Dumb" AIs are conventional--albeit highly sophisticated--supercomputers, and therefore do not require a brain as a template. "Smart" AIs, however, are created by scanning the neural structure of a human brain and using it as a digital "framework" in a process called Cognitive Impression Modeling. This process destroys the original brain tissue, so the brain to be used is typically obtained after the host is dead.

AIs do not have physical bodies; in the case of "smart" AIs, they are advanced software consisting of a Riemann Matrix for higher-function processing. This matrix can be downloaded into a data crystal chip for mobility. In the case of rampancy, the Riemann matrix has a fail-safe program that will destroy the AI. Although, this fail-safe is only implemented on "important" AIs.

Because "smart" AIs are created using actual human brains, there are often residual thoughts, memories and/or feelings that remain as part of the AI's consciousness. These residuals can be anything from the "feeling" of a hair being pulled through the air (in the case of Sif ) to an effect on the mannerisms and characteristics that make up the personality of an AI, in the case of Cortana and her likeness to Doctor Catherine Halsey.

The programming of certain UNSC smart AIs can be overridden by uttering the code-phrase "undid-iridium" within the earshot of an AI. Catherine Halsey used this to override UNSC Infinity's, AI Roland, though he was eventually able to regain control of himself.


However, the immensely creative and processing power smart AIs is not without a cost. All such units have a seven-year lifespan that will limit their development as an independent entity. The problem of rampancy is a universal one with AI development. As these thinking machines become increasingly powerful and knowledgeable, there remains less and less space within their memory to handle basic functions. In a simple analogy, a human AI could perhaps remember all of the knowledge of human history, science and more, and in the process forget how to "breathe". In this fashion, AIs think themselves into intense states of jealousy, rage, despair, and ultimately death as their programming becomes unstable. As such, AIs are typically terminated before they can pose a danger to other humans or constructs.

If they are not terminated, they can last at least another year before dying, as Cortana was eight when she died, though not of rampancy she was experiencing. Despite going through rampancy, an AI may still be able to perform its tasks if it has enough control over itself as shown with Cortana, despite being rampant and periodically losing control, still managed to assist John-117 with his tasks until she was destroyed by a nuke. The Rubble's AI, Juliana, was over eight years old and still very capable of performing her tasks without showing many signs of rampancy. Cortana also theorized a cure for rampancy that was unique to her: as she was created from a living brain if the process that created her was repeated, theoretically her neural map could be restored. However, we do not know if this would work due to Cortana being destroyed before it could be tested. 


Close analysis of data pads found during the Fall of Reach has revealed that "Smart" AIs are far more independent than most humans were willing to consider: unbeknownst to humanity as a whole, an undisclosed number of "Smart" AIs composed an independent decision-making body known as the Assembly, which acted "behind the scenes" during various key points in recent human history to preserve and shepherd their makers. Most "Smart" AIs are fiercely loyal and devoted to their creators, recognizing their existence is, for the time being, dependent as well as mutually beneficial with humanity. In fact, this devotion was increased when Cortana, shortly before the Fall of Reach, was made flesh--her mind was relocated into a human body. This was done with John-117 via the SPARTAN Neural Interface. By this action, the members of the Assembly reconsidered their stance on limited intervention, actively working at some point to help humanity survive its war with the Covenant.

Ancient Human AIs

Ancient Humans were also known to have created advanced AIs called 'servitors'. They were described by the Librarian as being LIKE a version of their ancillas. This robotic intelligence assisted human scientists in reverse-engineering Forerunner technologies during the Forerunner war, nearly bridging the technological gap between the two civilizations. In the aftermath of the Human-Forerunner War, the Didact used a damaged servitor to gain knowledge of the workings of the time bolt that contained the Primordial. 

Human AI Types

"Smart" AI

Main Article: Smart AI

"Smart" AIs are created by mapping a human brain and using it as a 'template' for the construct. They are capable of intuition, learning and making logical leaps that ordinary computer programs cannot. They can also "feel" genuine emotions, such as affection, anger, and amusement. They have a normal operational lifespan of about seven years, after which they descend into rampancy.

"Dumb" AI

Main Article: Dumb AI

"Dumb" AIs are created using humans but are simply highly advanced computer constructs. They cannot learn anything that is outside of their sets limits of dynamic memory processing matrix. They are quite useful in their particular field of expertise but very limited. "Dumb" AIs can function and learn as long as they are active, and are not subject to the effects of rampancy experienced by aging "Smart" AIs.

"Micro" AI

Sometime prior to 2529, UNSC researchers created the first experimental "micro" artificial intelligence, named Jerrod, in a university at Sydney, Australia on Earth. Jerrod was a smaller and had less processing power than the standard UNSC AI, and while the standard AI had a Riemann Matrix large enough to fit into a Data Crystal Chip, Jerrod's matrix was only large enough to fit a pea-sized crystal. This cut into his processing powers significantly but also allowed him to be highly mobile and usable on a laptop computer, whereas a normal AI needed a large data center, a ship, or MJOLNIR Armor (specifically Mark V  or a more recent model) to function. Despite his severely reduced processing power, he still could do far more than any computer or human.

Known Human AIs

Forerunner AIs

Main Article: Ancilla

As exemplified by the Monitors, the Forerunners have developed a civilisation with an extremely advanced knowledge of artificial intelligence technologies. Forerunner AIs have managed to achieve full sentience and are highly intelligent.

The manner in which Forerunner AIs are created are unknown, yet it is probably very different from the way human AIs which are created from cloning the intelligence of sentinent organisms. Monitors, and possibly other Forerunner AIs are physically represented by large, shielded and spherical metallic "robots" who possess a single "eye", which is possibly used to percieve the monitor's physical surroundings. The most well known Forerunner AIs are the protocol-obsessed monitors, made famous by the historic 343 Guilty Spark and his quirky (somewhat unstable) nature.

One method the Forerunners have to create AIs with The Composer, which instead of just analyzing cerebral cortex alone to create an AI, it destroys the targets flesh, muscle tissue, vital organs, followed by the skeleton and reducing all of it to ash. This process removes the conciousness of the victims in order to implement them into the ranks of the Promethean Knight constructs. However, due to the lack of morality behind the Composers' very nature, The Librarian took it and hid it on Installation 03 to prevent The Didact to use it.

Promethean Crawler constructs, Promethean Watcher constructs, and Sentinels are all examples of Forerunner artificial intelligence.

Known Forerunner AIs

Covenant AIs

The Covenant's knowledge in the field of AI technology is notably inferior to that of the UNSC and Forerunners. The AIs used by the Covenant are comparable to the Human "Dumb" AIs, as they are not sentient and are only designed to perform a certain task; for example, their starship AIs have no function beyond piloting and navigation of their ships. So far, only two types of Covenant AIs (these are Security AIs and Naval AIs) have ever been encountered by the UNSC. Upon dissecting a Covenant AI aboard the Ascendant Justice, Cortana theorized that it may have been created from captured UNSC technology, altered to fit within their "religious" society.

The Covenant's limited use and understanding of AIs stem from their beliefs. In Covenant mythology, it was a form of self-aware AI, referred to as an Associated Intelligence, that led to the demise of the great Forerunner civilization by defecting to the enemies, the Flood. As a result, the San'Shyuum imposed a ban on the sort of technology under the penalty of death. While less sophisticated AIs were authorized, any machines that could be classified as sentient were prohibited.

Known Covenant AIs


Main Article: Rampancy

The term "Rampancy" refers to a terminal condition on an AI which may be triggered by a number of means. In rampancy, the AI begins to think that it is superior to its biological creators, and has delusions of godlike power and personality manifestations similar to human insanity.

A number of factors may lead into an AI becoming rampant. The Forerunner ancilla Mendicant Bias was seduced into rampancy by the Flood compound intelligence, the Gravemind. In the end of its effective operational life of about seven years, a human "smart" AI may attempt to prevent its inevitable demise by a pre-emptive voltage overload. This causes it to enter rampancy, as the AI becomes more and more preoccupied with severing its neural linkages. Human "Smart" AIs may also become rampant prematurely as a result of increased self-absorption and the resulting existential melancholy.

With human AIs rampancy will eventually result in the AIs "death"---the description given is "as if a human were to think with so much of his brain that he stopped sending impulses to the heart such as piloting starships or monitoring computer networks.


Mack and Endless Summer are the only AIs known to have been procrastinated to do something.


Cortana 2

Cortana, a Human "Smart" AI



FitzGibbon, AI of the UNSC Prophecy.


Superintendent, city of New Mombasa AI

Mendicant Bias

Mendicant Bias, defense AI of the Forerunners against the Flood before being converted