Computer networks link computers lo

Computer networks link computers locally or by external communication lines and software allowing data to be exchanged rapidly and
reliably. The 2 between local area and wide area networks is,
however, becoming unclear. Networks are being used to perform increasingly diverse tasks, such as carrying e-mail, providing access to public databases,
and for 3 . Networks also allow users in one locality to share
resources.
Distributed systems use networked computers. PCs or 4
provide the user . Mainframes process 6
and return the results to the users. A user at his PC might make a query against a central database. The PC passes the query, written in a special language, to the mainframe, which then' the query,
returning to the user only the data requested. This allows both the network and the individual PC to operate efficiently.
In the 1980s, at least 100,000 8 were set up world-wide. As
9
orbit satellites have lowered the price of long-distance telephone calls, data can be transmitted more cheaply. In addition,
10 cable has been installed on a large scale, enabling vast
amounts of data to be transmitted at a very high speed using light signals. This will considerably reduce the price of network access, making global networks more and more a part of our professional and personal lives. Networks should
also improve our work!' and technical abilities.
distinction fibre-optic protocols synchronous
distributed systems LANs queries workstations