Understanding Computer Networks
collection of computers, and other devices that connect computer support in a single unit. Media computer network can be via wires or wireless computer network allowing users to mutually exchange information, such as documents and the data, can also do the same printing on printers and shared use of hardware and software that is connected to the network. Each computer, or devices that are connected in a network is called a node. In a computer network can have two, tens, thousands or even millions of nodes.

. The purpose of the computer network are:
* Sharing of resources: for example, shared usage of the printer, CPU, memory, hard drive* Communication: eg electronic mail, instant messaging, chat* Access to information: for example web browsing
In order to achieve the same goal, every part of the request and provide computer network services (service). Parties who request a service called the client (client) and that provides service is called servant (the server). The architecture is called client-server systems, and is used in almost all computer network applications.
Classification Based on the scale:
* Personal Area Network (PAN)* Campus area network (CAN)* Local Area Network (LAN)* Metropolitant Area Network (MAN)* Wide Area Network (WAN)* Global Area Network (GAN)
Based on the function: Basically every computer in a network that functions as a client and server. But there is a network that has a dedicated computer as a server and the other as a client. There is also a computer that has no special function as a server only. Thus, based on its function then there are two types of computer networks:
* Client-server
Namely computer network with a dedicated computer as a server. A service / service can be provided by a computer or more. An example is a domain such as www.detik.com lots served by a web server computer. Or it could be a lot of service / services provided by a single computer. Examples are jtk.polban.ac.id server which is a single computer with multi service ie mail servers, web servers, file servers, database servers and others.
*-To-peer Peer
Namely computer networks where each host can be also be a client and server simultaneously. For example in file sharing between computers on the Windows Network Neighbourhood Network have five computers (we give the name of A, B, C, D and E) which give the right of access to its files. At one point A to access the file share of B named data_nilai.xls and also gives access to files soal_uas.doc C. When accessing a file from B to A then A is functioning as a client and when A gives access to the files to C then A is functioning as a server. Both functions were performed by A the same time, such networks are called peer to peer.
Based on the network topology: Based on the [topology], computer networks can be divided into:
* Topology bus* Topology stars* Ring network* Mesh topology* Topology tree* Linear topology