The range of frequencies over which signal amplitude remains constant (within some limits) as it is passed through a system.

More specific definitions include:

a) The difference between the upper and lower limits of a frequency, often measured in megahertz (MHz).

b) The complete range of frequencies over which a circuit or electronic system can function with less than a 3 dB signal loss.

c) The information carrying capability of a particular television channel.

d) A measure of information capacity in the frequency domain. The greater the bandwidth of a transmission channel, the more information it can carry. e) In television, bandwidth is usually expressed in MHz.