Computer networking in Carnegie is the practice of linking computing devices together with hardware and software that supports data communications across these devices. Networks can be categorized in several different ways. One approach defines the type of network according to the geographic area it spans; Local area networks typically reach across a single home, whereas, wide area networks reach across cities, states, or even across the world. The internet is the world's largest public WAN. Computer networks also differ in their design; they may be client-server or peer-to-peer. Client-server networks, much more common in business, feature centralized server computers that store e-mail, web pages, files and applications. Conversely, all computers tend to support the same functions on a peer-to-peer network, more common in homes.