Artificial intelligence (or AI) is a computer-based simulation of the human thought process. It is a common feature in science-fiction, but as yet no true AI (IE, one capable of passing the Turing Test) has been created, and only very limited progress has been made on such simple subcomponents as facial recognition or beating world champion chess players at chess.
Many philosophers, including the John Searle, have advanced the view that artificial intelligence is an impossible goal. The main argument is that it would be impossible for a machine, a creation of man, to ever achieve actual understanding and comprehension of either language or the world around it, as the machine is simply a set of rules which process symbolic information. This argument is summarized by Searle's thought experiment, the Chinese Room.  Despite being a humanist, Searle's arguments reflect the popular religious thought that creation can never be as great as the Creator. Thus, his conclusions are self-evident truth to any theist, as a machine is simply a metal object.
Artificial intelligence was most popular between the 60's and the 80's, when computers were still new and misunderstood. Alan Turing was responsible for much of the fever of attempting to create intelligent computers, with his publication of the paper proposing the Turing Test.
The field is now divided into several sub-branches, which attempt to recreate some of the features and abilities of the human mind, without assuming that the features such as real intelligence, understanding or emotions are in any way possible for a computer.