Frequency: The amount of data that can be transmitted on a channel depends on the wave frequency-the cycles per second. Frequency is expressed in hertz: 1 cycle per second equals 1 hertz. The more cycles per second, the more data can be sent through that channel.
Bandwidth: Bandwidth is the difference between the highest and lowest frequencies that is, the range of frequencies. Data may be sent not just on frequency but on several frequencies within a particular bandwidth. Thus, the greater the bandwidth of a channel, the more frequencies it has available and hence the more data that can be sent through that channel. The rate of speed of data through the channel is expressed in bits per second (bps).
Channels that move data relatively slowly, like telegraph lines, are narrowband channels. Most telephone lines are voiceband channels, and they have a wider bandwidth than narrowband channels. Broadband channels (like coaxial cable, microwave circuits, and satellite systems) transmit large volumes of data at high speeds.