Spectral lines

What is artificial intelligence? And how does it relate to expert systems? It is generally acknowledged that artificial intelligence is the broader term, encompassing both practical expert systems and cognitive science, the latter concerned with modeling human intelligence. Yet computer scientists are not totally agreed on the definition of artificial intelligence. This is not surprising, given the difficulty of defining natural intelligence. Human intelligence, or the practical application of knowledge, covers the collection and classification of knowledge, its selective retrieval, and its processing to yield some usable result, as, for example, in making a decision to take a certain action.