A nanite was a microscopic molecular machine, a form of nanotechnology. Nanites had a variety of uses, such as in medicine, to alter or manipulate the inside of living cells.
Weapons and defences
The Borg Collective made use of nanites on their Diamond vessels as a method of disrupting enemy communication and computer systems. These nanites were injected into an enemy ship where they began to scramble the computer interface, causing chaos on the target vessels. (TNG video game: Armada)
- This served as a special ability among the Borg Diamond which, when used, caused the interface to move randomly across the screen making it difficult to issue commands to an infected unit.
The Heran Modality deployed nanites all over their homeworld of Hera, which worked as a method of suppressing enemy ground weaponry. This worked by the nanites affecting the power linkages of the weapons, making them useless in a battle on the planet, thus forcing invaders to make use of simpler methods to combat the Heran defense forces. (TNG novel: Infiltrator)
In the mirror universe, the Obsidian Order developed a way to use nanites as passive recording devices, to spy by secretly recording conversations. The Order's research and development team developed a way to deploy them, using miniature particle ejectors containing programmable cylinders containing thousands of nanites. These nanites were capable of recording through tissue from inside the lungs or intestines of a living being with some being capable of clinging to a target's hair or clothes for a day or so. Once loaded into the ejector, it was a simple matter to implant the machine to the users lips. After which, a certain amount of pressure activated the nanites which blew towards the target and recording everything relating to them. They were capable of being remotely triggered at a later time and once they were retrieved, it was possible to gain an entire day's worth of conversations from the machines as they worked together for redundancy.
The head of the Order, Enabran Tain, planned on using this technology on Gul Skrain Dukat in order to learn his secrets so that Tain could destroy his career. At the time, Tain did not share any of the secrets of the technology within the rest of the Klingon-Cardassian Alliance or even his own government. (DS9 novel: Dark Passions)
The short lived Borg-Romulan alliance made use of nanites that were not constructed from Borg technology to help regenerate the body of James Tiberius Kirk as a plot to use him against the Federation. (TOS novel: The Return)
Nanites were responsible for the legendary healing properties of the Ilaiyen Archipelago. This nanotechnology had been given to the Ilaiyenai by extra-planetary explorers sometime prior to or during the 13th century. (TOS - Constellations short story: "As Others See Us")
In 2257, Section 31's threat assessment system, Control use nanites to reanimate and control several agents such as Captain Leland and Lieutenant Kamran Gant. The nanites were able to withstand phaser blasts. However, Lieutenant Spock and Captain Philippa Georgiou were able to magnetize items to remove the nanites from them despite the pain.(DSC episodes: "Perpetual Infinity", "Through the Valley of Shadows", "Such Sweet Sorrow")
In 2366, Wesley Crusher experimented with nanites, causing them to evolve into sentience. After threatening the computer core of the USS Enterprise, these nanites were transported to planet Kavis Alpha IV to create their own civilization. (TNG episode: "Evolution")
In 2367, use of the nanites to defeat the Borg was blocked because a case was brought before the Federation to prevent their use without their consent (TNG novel: Vendetta) (Geordi Laforge: "The nanites have lawyers?!")
That same year, Elias Vaughn and Ruriko Tenmei used trillions of nanites to find and unwrite the code of Cren Veruda's artificial intelligence, which the Borg had found at Uridi'si. (DS9 - Mission Gamma novel: Lesser Evil)
In 2370, during the invasion of the Heran homeworld, the Klingon and Federation forces discovered their hand-held energy weapons to be useless due to the Heran use of nanites. (TNG novel: Infiltrator)
In 2376, Simon Tarses used medical nanites to treat injuries that Ro Laren suffered after Taran'atar's attack. They were able to limit the genetronic matrix's activity at the molecular level and prevented accidental metastasization. (DS9 novel: Warpath)