MIDI is an 8-bit computer language. Like all computer languages MIDI is constructed from 1s and 0s (so called bits).
In the MIDI language bits are grouped into units called bytes, as they are in all languages. The bytes in MIDI are 8 bits long.
Because the bytes in MIDI are 8 bits long it is said to be an 8-bit language. Other computer languages are 16-bit (16 bits in a byte) or even 24-bit, 32-bit, 64-bit, or 128-bit. MIDI is 8-bit because compared to many languages it is transmitted relatively slowly (for cost reasons) and therefore needs to be as small as possible to ensure that timing errors do not become noticeable.
In the MIDI language there are 256 different bytes. Each byte has a specific purpose.
MIDI bytes fall into one of 2 categories ...
By combining bytes together, MIDI messages are constructed.
There are 2 categories of MIDI message ...
All MIDI messages are constructed from at least 1 status byte and 1 data byte, often many many more.
Here is an example of a simple 3 byte MIDI message comprising a Status byte and 2 Data bytes. This message is telling a sound module set to respond on MIDI channel 1 to start playing a note (C3) at a velocity of 101.