The term data rate is used synonymously for transmission speed and transmission rate. It is the number of information units that are transmitted in a certain time via the transmission medium, via an interface or via a transmission channel.
The information units can be bits or bytes, characters, data blocks or frames that are transmitted in a certain time interval. The data rate is specified in bits per second (bit/s) or in kilobits per second (kbit/s), megabits per second (Mbit/s) or gigabits per second (Gbit/s) and is the reciprocal of the bit duration. For example, if the data rate is 100 Mbit/s, then the bit duration is 10 ns.