Artificial Intelligence (AI) is the attempt to build artificial systems that have intelligent behaviour. There are two main directions of research. One is to understand natural intelligence by the use of computer models. The other provides techniques and technology for building systems capable of intelligent decisions and actions. Thus AI is both a science and an engineering discipline. Applications of AI range from 'smart' controllers for household devices to computers that can converse in English, play games, conduct intelligent web searches or act as the brain of a robot.