A network is simply a group of computers that are connected so that their resources can be shared. Schools have networks. Computers used by students, teachers, and administrators are all connected. This saves the expense of having to buy peripheral equipment like printers for each computer. For instance, when a homework assignment is being printed in the school computer lab, the printer is being shared with all of the students. It would be very expensive if a school bought a printer for every computer. In addition, a network allows users to share files. If work is being done on a group project, a file can be saved to a central computer called a file server. This file can then be accessed from any other student computer in the school.

Networks are not limited to just a building or school campus. Networks can be an entire school district or all of the offices in a company. A school, for example, is connected to a main district office, as are all the other schools in a district. The Internet is the ultimate network, connecting millions of smaller networks.

Most connections are made by cable, but wireless connections are beginning to gain popularity. Cable can carry voice, data, or both. Homes may have modems that plug into telephone jacks. The telephone line carries voice signals when the telephone is plugged into the jack, but carries data signals (encoded to appear as if they were voice) when the modem is connected. There are other, faster connections to the Internet that are available, such as Digital Subscriber Line (DSL), cable, and T1, T3, or E1 lines. In some parts of the world Integrated Services Digital Network (ISDN) is used as well. Most of these technologies are used by businesses because of the significant cost. Some of the high-speed services are only available in a limited area. Improvements in communication devices and an ever increasing demand for high-speed links, however, will mean that in the next few years many home users should have access to these types of Internet connections.