The Standard MIDI File (or SMF) format allows musicians to share music that can be played back on any compatible MIDI instrument. The internet has enabled this to grow into a business where MIDI files of commercial songs can be purchased and downloaded to computer, and also a shareware community, where enthusiasts upload pieces for all to freely access, although these can vary greatly in both quality and accuracy! Once downloaded to your computer, the song can then be copied to a floppy disk or USB dongle and then loaded into your portable keyboard, or in some cases transferred directly over MIDI. Alternatively, the file can be played by your keyboard via MIDI from a software sequencer on your computer. When compared with an audio file of the same song, the MIDI File version is not only a fraction of the size, but when loaded into a portable keyboard enables you to change such things as the sounds used, the tempo, the key, and even which parts should sound or not, enabling you to learn, practise and play along with the song. Although they wouldnt like to admit it, this method is often the approach that professional remixers take when starting to work on rearranging an existing song.