According to the Musical Instrument Digital Interface (MIDI) protocol a MIDI event is a piece of data sent to a MIDI device to prompt it to do something at a certain time. The MIDI event contains two pieces of information: 1) the MIDI tick, which specifies at what time something should be done; and 2) the MIDI message, which specifies what should be done.
The status byte of a MIDI message is the first byte of the MIDI message, the value of which defines the type of the MIDI message.
The following are possible status bytes.
Note on status byte 0xFF
Sent over MIDI ports, the 0xFF status byte describes a "reset" message. The MIDI device that receives this message will reset itself to a default state, which usually means stopping all playback, resetting the song position to zero, and so on.
In a MIDI file, however, the 0xFF status byte means a "meta" message. Meta messages carry meta information about the MIDI song, including track names, end of track events, various text events, and other.
"Reset" messages and "meta" messages are completely different, even though they have the same status byte. One can distinguish between the two, however. The reset message is sent over MIDI ports and is usually user generated (e.g., by pressing a button, rather than stored in a MIDI song). The meta message is stored in MIDI files, but never sent over MIDI ports.
Musical Instrument Digital Interface (MIDI)