| computer network
also called NETWORK, two or more
computers that are connected with one another for the
purpose of communicating data electronically. Besides
physically connecting computer and communication
devices, a network system serves the important function
of establishing a cohesive architecture that allows a
variety of equipment types to transfer information in a
near-seamless fashion. Two popular architectures are ISO
Open Systems Interconnection (OSI) and IBM's Systems
Network Architecture (SNA).
Two basic network types are local-area networks
(LANs) and wide-area (or long-haul) networks. LANs
connect computers and peripheral devices in a limited
physical area, such as a business office, laboratory, or
college campus, by means of permanent links (wires,
cables, fibre optics) that transmit data rapidly. A
typical LAN consists of two or more personal computers,
printers, and high-capacity disk-storage devices called
file servers, which enable each computer on the
network to access a common set of files. LAN operating
system software, which interprets input and instructs
networked devices, allows users to communicate with each
other; share the printers and storage equipment; and
simultaneously access centrally located processors,
data, or programs (instruction sets). LAN users may also
access other LANs or tap into wide-area networks. LANs
with similar architectures are linked by
"bridges," which act as transfer points. LANs
with different architectures are linked by
"gateways," which convert data as it passes
between systems.
Wide-area networks connect computers and smaller
networks to larger networks over greater geographic
areas, including different continents. They may link the
computers by means of cables, optical fibres, or
satellites, but their users commonly access the networks
via a modem (a device that allows computers to
communicate over telephone lines). The largest wide-area
network is the Internet , a collection of networks and
gateways linking millions of computer users on
every continent.
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