Science fiction deals in many ways with a number of sentient devices:

• computer: a machine intelligence; an artificial brain
• robot: a mechanical man
  • the word comes from a Czech word meaning "servitude" or "work."
  • first appeared in Karel Capek's play R.U.R. (Rossum's Universal Robots) in 1921
• android: an artificial human
  • the term means "man-like"
  • unlike robots, androids generally appear virtually indistinguishable from humans
• cyborg: a machine/human hybrid, i.e., a human with mechanical parts
  • the word itself is a contraction of the term "cybernetic organism."

The paradigm for science fiction's presentation of fearful machines revolves around two central fears:

• fear of mechanization--humans will be reduced to machines (see "The Machine Stops" by E.M. Forster)
• fear of humans remaining organic but finding themselves trapped in machines (see "I Have No Mouth and I Must Scream" by Harlan Ellison)

The laws of robotics are an attempt to counteract these fears by building safeguards into such machines.

Isaac Asimov is generally credited with creating these laws and writing a series of short stories (collected in I, Robot) about the application of the laws.

Asimov's editor John W. Campbell always said that Asimov came up with the laws. Asimov said that Campbell did. The truth is probably somewhere in between.

Nevertheless, Asimov published two robot stories--"Robbie" and "Reason"--which introduced positronic robots and alluded to restrictions on robot behavior.

The three original laws were first propounded in toto in "Runaround" (1942).

These laws are so ingrained in the conventions of science fiction that most authors routinely refer to the laws or explain why they are not in effect.

The Three [Original] Laws of Robotics:

• First Law: A robot may not injure a human being, or, through inaction, allow a human being to come to harm.
• Second Law: A robot must obey the orders given it by human beings except where such orders conflict with the First Law.
• Third Law: A robot must protect its existence as long as such protection does not conflict with the First or Second Law.

See "With Folded Hands" by Jack Williamson for a very scary extrapolation of the logical consequences of Asimov's Laws.

Asimov added a fourth, or Zeroth, Law in Robots and Empire (1985):

• Zeroth Law: A robot may not injure humanity or, through inaction, allow humanity to come to harm.
• First Law, revised: A robot may not injure a human being or, through inaction, allow a human being to come to harm.