Android

Androids were sentient, highly advanced, robotic lifeforms. They were made to imitate humanoid functions and characteristics. Although they often appeared to be life-like, they were synthetic and did not contain any crucial biological components, thus distinguishing them from cybernetic organisms.

History
Sentient androids were officially recognized as free-thinking lifeforms in 2365 by Captain Phillipa Louvois of Starfleet's Judge Advocate General's Corps, who granted such creatures as "having the freedom to choose" when the status of a sentient android (Lieutenant Commander Data) came into question by the Associate Chair of Robotics at the Daystrom Technological Institute that year.

Alternate Universes
In the Cryptic universe, there was wide scale development of androids after the success of Doctor Noonien Soong's Soong-type androids. By 2409, androids were serving in both Starfleet and the Klingon Defense Force.