MIDI Clock is a measure driven pulse (beat) clock. It carries Play, Stop, Forward, and Backward commands as well as tempo data. MIDI clock also has the unique ability to slew to tempo changes, i.e. speed-up or slow-down when driven by a tempo map for example. A master sequencer such as Tracktion generates MIDI clock and controls the tempo map. This clock is then sent to rhythm machines, outboard (hardware-based) sequencers and other software-based synth/sequencer combo programs such as Reason. These devices and programs usually benefit from external tempo/measure control and this is why they are often capable of receiving MIDI clock.

Unlike the measure driven pulse of MIDI clock, MIDI timecode (MTC) is time-based only relating to hours, minutes, seconds and frames, not measures or tempo. SMPTE is basically a higher resolution time-based clock. But MTC has been widely adopted by the audio industry and is slowly becoming the timecode norm.