When data is sent over a computer network, it is broken up into small chunks called packets. Each packet contains source and destination address information. The packet, along with the address information, is called a frame. It also contains information that describes how to put all of the packets back together again at the destination. The bandwidth determines the number of packets that can be transmitted within a fixed period of time.

Bandwidth is measured in bits per second and is usually denoted by any of the following units of measure:

NOTE: 1 byte is equal to 8 bits, and is abbreviated with a capital letter B. 1 MB/s is approximately 8 Mb/s.

The figure shows how bandwidth on a network can be compared to a highway. In the highway example, the cars and trucks represent the data. The number of lanes on the highway represents the amount of cars that could travel on the highway at the same time. An eight-lane highway can handle four times the number of cars that a two-lane highway can hold.

The amount of time it takes data to travel from source to destination is called latency. Like a car traveling across town that encounters stop lights or detours, data is delayed by network devices and cable length. Network devices add latency when processing and forwarding data. When surfing the Web or downloading a file, latency does not normally cause problems. Time critical applications, such as Internet telephone calls, video, and gaming, can be significantly affected by latency.