MIDI
Stands for Musical Instrument Digital Interface. A special interface that lets your computer control musical instruments, such as a synthesiser, keyboard or drum machine. To create a MIDI setup you need a MIDI interface for your PC- which is often part of a sound card- and a cable that runs to your musical instrument
MIDI file
File stored on your PC that contains musical notes and sound information that can be sent via a MIDI interface card to musical instrument. Midi files can also contain information that describes the type of sound played as well as the note. For example, to inform the synthesiser to sound like a piano or trumpet
MP3 is an increasingly popular way to store audio in electronic format. The MP3 format compresses audio files in such a way that the file size is relatively small, but the song sounds near perfect. You can identify MP3 files because they end in the ".mp3" extension. Typically 1 MB is equal to one minute of music or several minutes for spoken word/audiobooks. MP3 is big news and a controversial technology within the music industry because it allows musicians to distribute their music directly over the Internet, bypassing record companies. For more information, check out the site below http://www.mp3.com
midi devices usually manifest themselves as a keyboard contoller but can also creep up as drum pads or even a special guitar midi controller. midi is a language that describes how soft a key was played, how long a note was played.