Several types of networks exist, from small, two-station arrangements to networks that interconnect offices in many cities:

Local area networks. The smallest office network is referred to as a local area network (LAN). A LAN is formed from computers and components in a single office or building. A LAN can also be built at home from the same components used in office networking, but, as you’ll see later, special home-networking components now exist to allow the creation of what can be called a home area network (HAN).

Home area networks. A home area network (HAN) often uses the same hardware components as a LAN, but it is mainly used to share Internet access. Power line, low-speed wireless, and phoneline networks are used primarily in HAN rather than LAN environments. HANs are often referred to as small-office /home-office (SOHO) LANs.

Wide area networks. LANs in different locations can be connected together by high-speed fiber-optic, satellite, or leased phone lines to form a wide area network (WAN).

The Internet. The World Wide Web is the most visible part of the world’s largest network, the Internet. Although many users of the Internet still use modems over a dialup connection rather than a LAN or WAN connection, any user of the Internet is a network user. The internet is really a network of networks, all of which are connected to the Internet is a network user. The Internet is really a network of networks, all of which are connected to each other through the TCP/IP protocol. Programs such as Web browsers, File Transfer Protocol (FTP) clients, and newsreaders are some of the most common ways users work with the Internet.

Intranets. Intranets use the same Web browsers and other software and the same TCP/IP protocol as the public Internet, but intranets exist as a portion of a company’s private network. Typically, intranets comprise one or more LANs that are connected to other company networks, but, unlike the Internet, the content is restricted to authorized company users only. Essentially, an intranet is a private Internet.

Extranets. Intranets that share a portion of their content with customers, suppliers, or other businesses, but not with the general public, are called extranets. As with intranets, the same Web browsers and other software are used to access the content.