Standard MIDI files (SMF) are written for General MIDI equipment (software or keyboards with a disk drive or a sequencer). They are prerecorded pieces of music stored on a floppy disk. Think of a collection of songs (like a compact disc) and take out the vocals, then you have MIDIFILE. Because they are stored in the digital format editing is a breeze. For example, to make the song lower in pitch if a singer can't sing that high, or to slow the song down so a musician can learn it, you can use a MIDFILE. Most singers use them as backing tracks (Karaoke bars love them) and a lot of instrumentalists (guitarists, sax players etc) use them as a template to practice solos over. Musicians think it is a great way to learn songs, and computer users like to put songs into multimedia applications. Beware of copyright restrictions when doing this.