Normal computers can only perform complicated calculations and solve logical problems. They can be programmed to play chess. But it cannot play chess better than the person who programmed it. It sorts out many possible consequences of a move and makes an actual move. But intelligence is not merely reasoning, analysing and decision making. It also involves grasping a situation and deciding about how to tackle it. Artificial intelligence requires a computer which can first learn the rules of any specific signal processing and then apply them to solve the related problem. Learning and adaptive computers are developed nowadays. Experiments are being done to define intelligence clearly and build it into computers, even though for specific jobs.