Different physical media support the transfer of bits at different speeds. Data transfer is usually discussed in terms of bandwidth and throughput.

Bandwidth is the capacity of a medium to carry data. Digital bandwidth measures the amount of data that can flow from one place to another in a given amount of time. Bandwidth is typically measured in kilobits per second (kb/s) or megabits per second (Mb/s).

The practical bandwidth of a network is determined by a combination of factors:

Physical media properties, current technologies, and the laws of physics all play a role in determining available bandwidth.

The table shows the commonly used units of measure for bandwidth.