Unlike a robot, which is built from metal and electronic components and is clearly a machine, an android is an artificial being that looks like a man. The term "android" was first used in 1727 to describe the attempts of 13th century alchemist Albertus Magnus to create an artificial man. The first science fiction story that used the term "androids" seems to have been in Jack Williamson’s novel The Cometeers (1936).
Clifford Simak wrote a series of stories in the 1950s about androids that were treated as slaves by their human creators. Robert Silverberg wrote about androids in Tower of Glass (1970) and C.J. Cherryh in Port Eternity (1982).
Probably the most famous science fiction story about androids is the 1968 Phillip K. Dick novel, Do Androids Dream of Electric Sheet?, in which incredibly human-like androids, banned from Earth, fight back against their creators. The book formed the basis of the film Blade Runner starring Harrison Ford.
As for the most famous android in science fiction, that honor goes to Lieutenant Data of Star Trek: The Next Generation. He is the first android to be admitted to Starfleet, although with his electrical system, he is part robot. Lt. Data serves under Captain Picard aboard the Enterprise-D. Data was built by Dr. Noonian Soong, Earth’s foremost robotic scientist.