More and more, it is networks that connect us. People communicate online from everywhere. Conversations in classrooms spill into instant message chat sessions, and online debates continue at school. New services are being developed daily to take advantage of the network.

Rather than developing unique and separate systems for the delivery of each new service, the network industry as a whole has adopted a developmental framework that allows designers to understand current network platforms, and maintain them. At the same time, this framework is used to facilitate the development of new technologies to support future communications needs and technology enhancements.

Central to this developmental framework, is the use of generally-accepted models that describe network rules and functions.

Within this chapter, you will learn about these models, as well as the standards that make networks work, and how communication occurs over a network.