Analog bandwidth
Analog bandwidth typically refers to the frequency range of an analog electronic system. For example, analog bandwidth could be used to describe the range of frequencies radiated by an FM radio station. Analog bandwidth could also refer to the range of frequencies that can propagate down a copper cable. Analog bandwidth is described in units of frequency, or cycles per second, which is measured in Hz. There is a direct correlation between the analog bandwidth of any medium and the data rate in bits per second that the medium can support.

Digital bandwidth
Digital bandwidth is a measure of how much information can flow from one place to another, in a given amount of time. Digital bandwidth is measured in bits per second. When dealing with data communications, the term bandwidth most often signifies digital bandwidth.

Throughput refers to actual, measured bandwidth. In some cases, it is further restricted to only include actual data, discarding any protocol overhead, such as headers, trailers, and protocol messages, from the computed totals. Regardless of the exact method of computation, the actual throughput is often far less than the maximum possible digital bandwidth of the medium that is being used. Many factors affect throughput, including the medium, the distance, noise, and the protocols used.

When designing a network, it is important to consider the theoretical bandwidth. The network will never be faster than the medium will allow. A related consideration is the amount of bandwidth that the user applications require. Figure illustrates different methods of connecting to the Internet and their corresponding bandwidths, in Kbps. Also shown in Figure are some typical Internet applications and their corresponding bandwidth needs.