Bandwidth Bandwidth, informally, is the amount of information we can send through a cable in a second. When we talk about the bandwidth of an Ethernet cable, say it is 10 megabits. This means we can send data at a rate of 10 million bits per second through the cable. Formally it is difficult to define bandwidth. Electrical engineers, and computer scientists often define bandwidth in different ways, and use different units.
Electrical engineers define bandwidth as the highest frequency sine wave that can be carried.
The define bandwidth using hertz, or cycles per second. By that definition, a television channel has a bandwidth of about 10 megahertz, or 10 million cycles per second. Computer scientists might define bandwidth in terms of baud. Baud is the number of state transitions per second the line will handle. A state transition is a change of voltage on the line.