01In plain English
MIDI does not record sound. It records which notes were played, when, and how hard. That data can drive any virtual instrument, and every note can be edited afterwards.
02Why it matters when you are choosing
MIDI is how most music is written in a DAW. Good MIDI editing makes it quick to fix timing, change a melody or swap instruments.
03What to check
Ask the vendor
Check the MIDI editor, support for your keyboard or controller, and whether the app includes instruments to play the notes.