Computer networking, not to be confused with social networking, is the practice of linking two or more computing devices for the purpose of sharing data. Computer networks are built using a combination of hardware and software.

Computer networks can be categorized in several ways. One approach defines a type of network based on the geographic area it covers. For example, local area networks (LANs) typically cover a single home, school, or small office building, while wide area networks (WANs) span cities, states, or even the entire world. The Internet is the world's largest public WAN.

Computer networks also differ in their design approach. The two basic forms of network design are called client-server and peer-to-peer.

Client-server networks contain centralized server computers that store e-mail, web pages, files, and applications that can be accessed by client computers and other client devices. In a peer-to-peer network, on the other hand, all devices typically support the same functions. Client-server networks are common in businesses, and peer-to-peer networks are common in homes.