Almost everything around you is part of a network or is based on a network whether in nature or in human society, the network connects the different parts of things, facilitates communication and cooperation, and shows that the network of resources as a whole is much greater than the sum of its parts. It is for our today’s society is a highly complex huge system, between people, between the departments, enterprises and between enterprises there are thousands of silk wan links, cooperation and coordination become the main social work mode, and as an auxiliary tool of human computer must adapt to this kind of mode, computer network so arises at the historic moment.
