This chapter introduces the concepts of data flow, queue models, structure and topology, performance measures, traffic, channel capacity, latency, protocols, and more representative architectures of computer networks. The queuing theory, which encompasses the theory of telephone traffic, provides an important model for the analysis of quantitative performance, correlating the most interesting computer networks. A generic computer network can be defined as a set of autonomous computers interconnected so that no machine completely controls the others. Computer networks have been developed to enable the sharing of facilities and the distribution of resources among users. Long distance networks, for economic reasons normative, used telephone links, which resulted in links with lower speeds. With the launch of long-term optical networks distance network, which includes OPGW networks, transmission over high voltage lines, from electricity, transmission rates have risen considerably. The delay, or latency, of the network is an important parameter when dealing with voice transmission in real time.