Bandwidth can be defined as follows:

The range of frequencies that can pass over a given transmission channel. The bandwidth determines the rate at which information can be transmitted through the circuit: the greater the bandwidth, the more information that can be sent in a given amount of time. Bandwidth is typically measured in bits per second. Increasing bandwidth potential has become a high priority for network planners due to the growth of multimedia, including videoconferencing, and the increased use of the Internet.

The signal-to-noise ratio (SNR) of a modulated signal is tested within a range of frequencies on either side of the carrier frequency. This range is also called a bandwidth. In the case of videodiscs, it is often 15 kilohertz (kHz) on either side.