concept

Bandwidth

The range of frequencies a channel can carry, measured in hertz (Hz) - and the resource that really decides how much a channel can move. In the Shannon-Hartley theorem, capacity grows linearly with bandwidth: double the bandwidth, double the data rate. A copper phone line has a few kilohertz of bandwidth and carries tens of kilobits per second; a fibre-optic strand has terahertz of bandwidth and carries terabits. Note the distinction: bandwidth (Hz, the "size of the pipe") is not bit-rate (bits/s, the information actually flowing through it) - though casual speech conflates them.