MIDI is initials for Musical Instrument Digital Interface. That is a protocol created in the 80s, to allow the communication between electronic musical instruments and any other device that also has a MIDI interface.
This protocol works through a message exchange between the devices. The messages are sent and received electronically by bits. Those messages are read by musical instruments to produce sounds according to what is defined.
Some of these messages are control messages
In the chart below, there is a shortlist of the MIDI control codes in decimal and hexadecimal.
AUTHOR: JONATAS CASTRO