From http://www.w3schools.com (Copyright Refsnes Data)
Sound can be stored in many different formats.
The MIDI (Musical Instrument Digital Interface) is a format for sending music information between electronic music devices like synthesizers and PC sound cards.
The MIDI format was developed in 1982 by the music industry. The MIDI format is very flexible and can be used for everything from very simple to real professional music making.
MIDI files do not contain sampled sound, but a set of digital musical instructions (musical notes) that can be interpreted by your PC's sound card.
The downside of MIDI is that it cannot record sounds (only notes). Or, to put it another way: It cannot store songs, only tunes.
Click here to play The Beatles.
The upside of the MIDI format is that since it contains only instructions (notes), MIDI files can be extremely small. The example above is only 23K in size but it plays for nearly 5 minutes.
The MIDI format is supported by many different software systems over a large range of platforms. MIDI files are supported by all the most popular Internet browsers.
Sounds stored in the MIDI format have the extension .mid or .midi.
The RealAudio format was developed for the Internet by Real Media. The format also supports video.
The format allows streaming of audio (on-line music, Internet radio) with low bandwidths. Because of the low bandwidth priority, quality is often reduced.
Sounds stored in the RealAudio format have the extension .rm or .ram.
The AU format is supported by many different software systems over a large range of platforms.
Sounds stored in the AU format have the extension .au.
The AIFF (Audio Interchange File Format) was developed by Apple.
AIFF files are not cross-platform and the format is not supported by all web browsers.
Sounds stored in the AIFF format have the extension .aif or .aiff.
The SND (Sound) was developed by Apple.
SND files are not cross-platform and the format is not supported by all web browsers.
Sounds stored in the SND format have the extension .snd.
The WAVE (waveform) format is developed by IBM and Microsoft.
It is supported by all computers running Windows, and by all the most popular web browsers.
Sounds stored in the WAVE format have the extension .wav.
MP3 files are actually MPEG files. But the MPEG format was originally developed for video by the Moving Pictures Experts Group. We can say that MP3 files are the sound part of the MPEG video format.
MP3 is one of the most popular sound formats for music recording. The MP3 encoding system combines good compression (small files) with high quality. Expect all your future software systems to support it.
Sounds stored in the MP3 format have the extension .mp3, or .mpga (for MPG Audio).
The WAVE format is one of the most popular sound format on the Internet, and it is supported by all popular browsers. If you want recorded sound (music or speech) to be available to all your visitors, you should use the WAVE format.
The MP3 format is the new and upcoming format for recorded music. If your website is about recorded music, the MP3 format is the choice of the future.
From http://www.w3schools.com (Copyright Refsnes Data)