The number of bits, characters, or blocks passing through a data communication system, or portion of that system. Note 1: Throughput may vary greatly from its theoretical maximum. Note 2: Throughput is expressed in data units per period of time; e.g., in the DDN, as blocks per second. 2. The maximum capacity of a communications channel or system. 3. A measure of the amount of work performed by a system over a period of time, e.g., the number of jobs per day.