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"Connecting Near and Far with Networks Two basic types of networks are distinguished by the area they cover. A local area network (LAN) lets people at one site exchange data and share the use of hardware and software from a variety of computer manufacturers. LANs offer companies a more cost-effective way to link computers than linking terminals to a mainframe computer. The most common uses of LANs at small businesses, for example, are office automation, accounting, and information management. LANs can help companies reduce staff, streamline operations, and cut processing costs. LANs can be set up with wired or wireless connections. A wide area network (WAN) connects computers at different sites via telecommunications media such as phone lines, satellites, and microwaves. A modem connects the computer or a terminal to the telephone line and transmits data almost instantly, in less than a second. The internet is essentially a worldwide WAN. Communications companies, such as AT&T, Verizon, and Sprint, operate very large WANs. Companies also connect LANs at various locations into WANs. WANs make it possible for companies to work on critical projects around the clock by using teams in different time zones. Several forms of WANs—intranets, virtual private networks (VPN), and extranets—use internet technology. Here we’ll look at intranets, internal corporate networks that are widely available in the corporate world, and VPNs. Although wireless networks have been around for more than a decade, they are increasing in use because of falling costs, faster and more reliable technology, and improved standards. They are similar to their wired LAN and WAN cousins, except they use radio frequency signals to transmit data. You use a wireless WAN (WWAN) regularly when you use your cellular phone. WANs’ coverage can span several countries. Telecommunications carriers operate using wireless WANs. Wireless LANs (WLAN) that transmit data at one site offer an alternative to traditional wired systems. WLANs’ reach is a radius of 500 feet indoors and 1,000 feet outdoors and can be extended with antennas, transmitters, and other devices. The wireless devices communicate with a wired access point into the wired network. WLANs are convenient for specialized applications where wires are in the way or when employees are in different locations in a building. Hotels, airports, restaurants, hospitals, retail establishments, universities, and warehouses are among the largest users of WLANs, also known as Wi-Fi. For example, the Veterans Administration Hospital in West Haven, Connecticut, recently added Wi-Fi access in all patient rooms to upgrade its existing WLAN to improve patient access, quality, and reliability. The new WLAN supports many different functions, from better on-site communication among doctors and nurses through both data transmission and voice-over-internet phone systems to data-centric applications such as its Meditech clinical information system and pharmacy management."