Network basic

A computer network is a communication system that connects two or
more computers so that they can exchange information and share resources.
Networks can be set up in different arrangements to suit users’ needs.

Terms 
There are a number of specialized terms that describe computer networks.
These terms include

• Node —any device that is connected to a network. It could be a computer,
printer, or data storage device.
• Client —a node that requests and uses resources available from other
nodes. Typically, a client is a user’s microcomputer.
• Server —a node that shares resources with other nodes. Dedicated servers specialize in performing specific tasks. Depending on the specific task,
they may be called an application server, communication server, database
server, file server, printer server, or Web server.
• Directory server —a specialized server that manages resources, such as
user accounts, for an entire network.
• Host —any computer system that can be accessed over a network.
• Switch —central node that coordinates the flow of data by sending messages directly between sender and receiver nodes. A hub previously filled
this purpose by sending a received message to all connected nodes, rather
than just the intended node.
 • Network interface cards (NIC) —as discussed in Chapter 6, these are
expansion cards located within the system unit that connect the computer
to a network. Sometimes referred to as a LAN adapter.
• Network operating systems (NOS) —control and coordinate the activities of all computers and other devices on a network. These activities
include electronic communication and the sharing of information and
resources.
 • Network administrator —a computer specialist responsible for efficient
network operations and implementation of new networks.
A network may consist only of microcomputers, or it may integrate microcomputers or other devices with larger computers. Networks can be controlled
by all nodes working together equally or by specialized nodes coordinating and
supplying all resources. Networks may be simple or complex, self-contained or
dispersed over a large geographical area.