Interconnected systems differ according to the tasks in the access to data, in their provision, in the distribution of loads, functions and computing power. These requirements led to the development of various interconnected systems in the 1990s, such as the data network, which improves access to distributed databases. The functional network with access to internal and remotesystems. The availability network, which ensures fault tolerance. The load network with which the computers are evenly utilized. The peripheral network, which allows several systems to use expensive peripheral devices. And the communication network for better information exchange between the computer systems.