The Three Laws of Robotics
Created | Updated Jan 28, 2002
1) A robot may not injure a human being, or through inaction allow a human being to come to harm.
2) A Robot must obey the orders given it by human beings except where such orders would conflict with the First Law.
3) A robot must protect its own existence, as long as such protection does not conflict with the First or Second Law.
Later, in his robot novels, Asimov introduced a new law above all the others, albeit an unofficial one only adopted by two robots, one of which died after using it. But it was a nice thought anyway!
Zeroth Law - A robot may not harm humanity, or through inaction allow humanity to come to harm.
Since this became the most important law, the other 3 were modified accordingly.
Over time, scientists and science fiction writers everywhere decided that these laws were quite a good idea, so you'll find them cropping up in all sorts of places now, not just in the writings of Asimov.