The definition of artificial intelligence can be divided into two parts, namely "artificial" and "intelligence". "Artificial" is easier to understand and less controversial. Sometimes we have to consider what human beings can do, or whether human intelligence is high enough to create artificial intelligence, and so on. But in general, "artificial system" is an artificial system in the usual sense. Artificial intelligence is a very extensive science, which is composed of different fields, such as machine learning and computer vision. Generally speaking, one of the main goals of artificial intelligence research is to enable machines to be competent for some complex tasks that usually require human intelligence. But in different times, different people have different understandings of this "complex work".