Deﬁnition: A computer network is a group of computers that are connected together to communicate and share resources such as ﬁles and printers. Networks include network media, such as a cable to carry network data, network adapter hardware to translate the data between the computer and the network media, a network operating system to enable the computer to recognize the network, and a network protocol to control the network communication.
Figure: A computer network.
Network Interface Card
In order to allow computers to communicate over a network, they need to have a net- work interface card. This card can be either built in to the motherboard, or it can be installed as an adapter card in an expansion port or slot.
There are two primary network models, which are design speciﬁcations for how the computers and other nodes on a network can interact.
A client/server network is a network in which computer functionality is divided into two roles: server computers, which provide services and control network operations, and client computers, which use the services provided by the servers. Typically, there is at least one server providing central authentication services. Servers also provide access to shared ﬁles, printers, hardware, and applications. In client/server networks, processing power, management services, and administrative functions can be concentrated where needed, while clients can still perform many basic end-user tasks on their own.
A peer-to-peer network is a network in which resource sharing, processing, and communications control are completely decentralized. All clients on the network are equal in terms of providing and using resources, and users are authenticated by each individual workstation. Peer-to-peer networks are easy and inexpensive to implement. However, they are practical only in very small organizations, due to the lack of central data storage and administration. In a peer-to-peer network, user accounts must be duplicated on every workstation from which a user accesses resources. Such distribution of user information makes maintaining peer-to-peer networks difficult, especially as the network grows. Consequently, peer-to-peer networks should not exceed 10 computers.