Robot is from the Czech word robota which means labourer.
The word robot was first used by Karel Capek in his play R.U.R. (Rossum's Universal Robots) (written in 1920; first performed 1921; performed in New York 1922; English edition published 1923). 1. Although Capek's robots were organic artificial humans, the word robot is nearly always used to refer to mechanical humans. The term android can mean either one of these, while a cyborg would be a creature that is a combination of organic and mechanical parts.
Once the stuff of science fiction, the use of very simple robots is now a commonplace in many areas of industry, and particularly the automotive industry, where they have been programmed to replace human labour in many simple repetitive tasks.
Since very shortly after the birth of the concept of robots, humans have feared that they would be replaced by their own creations. Frankenstein (1818), sometimes called the first science fiction novel, has become synonymous with this theme, which was continued in such classic films as Metropolis, The Terminator, and Blade Runner. Serious speculation on this theme has continued to the present day, see for example "Why the future doesn’t need us", by Bill Joy (Wired, April 2000, ), and clanking replicators.