Nanobot

A nanobot is a nanotechnological robot, that is, a robot whose operating components are molecular and whose size is comparable to biological cells. As no nanobots have so far been created, they remain a hypothetical concept at this time.

Since nanobots are microscopic in size, it would be necessary for very large numbers of them to work together to perform macroscopic tasks. These nanobot swarms, also sometimes called utility fog or "goo" (as in grey goo and its less common variants) are found in many science fiction stories.

Medical nanotechnology[?] is often expected to utilize nanobots injected into the patient to perform their treatment on a cellular level.