Definition: - In computer networks, bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps). Occasionally, it is expressed as bytes per second (Bps) or in higher units like Mbps (millions of bits per second). A 28.8 modem can deliver 28,800 bps, a T1 line is about 1.5 Mbps. A modem that works at 57,600 bps has twice the bandwidth of a modem that works at 28,800 bps.
This is a measure of the amount of data that can be transmitted over communication or network lines via the Internet. The higher the bandwidth, the greater will be the amount of information that can be transmitted. Bandwith can also be described as a relative range of frequencies that can carry a signal on a transmission medium.

Bandwidth in electronic communication: - Bandwidth is the width of the range (or band) of frequencies that an electronic signal uses on a given transmission medium. In this usage, bandwidth is expressed in terms of the difference between the highest-frequency signal component and the lowest-frequency signal component. Since the frequency of a signal is measured in hertz (the number of cycles of change per second), a given bandwidth is the difference in hertz between the highest frequency the signal uses and the lowest frequency it uses. A typical voice signal has a bandwidth of approximately three kilohertz (3 kHz); an analog television (TV) broadcast video signal has a bandwidth of six megahertz (6 MHz) - some 2,000 times as wide as the voice signal.

Bandwidth in computer networks: - Bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps). Occasionally, it is expressed as bytes per second (Bps). A modem that works at 57,600 bps has twice the bandwidth of a modem that works at 28,800 bps. In general, a link with a high bandwidth is one that may be able to carry enough information to sustain the succession of images in a video presentation.
It should be remembered that a real communications path usually consists of a succession of links, each with its own bandwidth. If one of these is much slower than the rest, it is said to be a bandwidth bottleneck.

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