Computer Network:

A network is a group of computers connected together in a way that allows information to be exchanged between the computers.

Packet:

A piece of a message transmitted over a packet-switching network. One of the key features of a packet is that it contains the destination address in addition to the data. In IP networks, packets are often called datagrams. 

Local Area Network (LAN):

Local area network technologies connect many devices that are relatively close to each other, usually in the same building.

Wide Area Network (WAN):

Wide area network technologies connect a smaller number of devices that can be kilometers apart.

Node:

A node is anything that is connected to the network. While a node is typically a computer, it can also be something like a printer or CD-ROM tower.

Media Access Control (MAC):

This is the physical address of any device -- such as the NIC in a computer -- on the network. The MAC address, which is made up of two equal parts, is 6 bytes long. The first 3 bytes identify the company that made the NIC. The second 3 bytes are the serial number of the NIC itself.

IP Address:

An IP address is an alphanumeric label assigned to computers and other devices that connect to a network using an internet protocol. This address allows these devices to send and receive data over the internet. Each device that is capable of connecting to the internet has a unique IP address.

Bus Topology:

All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systemsuse a bus topology.

Ring Topology:

All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances.

Network Token:

A token is a special series of bits that travels around a token-ring network. As the token circulates, computers attached to the network can capture it. The token acts like a ticket, enabling its owner to send a message across the network. There is only one token for each network, so there is no possibility that two computers will attempt to transmit messages at the same time.

Star Topology:

In a star network, each node is connected to a central device called a hub. The hub takes a signal that comes from any node and passes it along to all the other nodes in the network. A hub does not perform any type of filtering or routing of the data. It is simply a junction that joins all the different nodes together.

Tree Topology:

A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable.

Protocol:

An agreed-upon format for transmitting data between two devices. The protocol determines the following:

Peer-Peer Architecture:

Often referred to simply as peer-to-peer, or abbreviated P2P, a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler, but they usually do not offer the same performance under heavy loads.

Client/Server Architecture:

Client-server architecture (client/server) is a network architecture in which each computer or process on the network is either a client or a server.

Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.