Media Files and Players
These are some of the most common types you’ll run into:
.wav — the oldest Microsoft type of sound files. Most sounds that you hear at startup and such, inclucing “You’ve got mail” are waves.
.mid — Most instrumental music on web pages are MIDI files. Rather than representing musical sound directly, MIDI files transmit information about how a song should sound that is then processed by your sound card. WAV files represent musical sound directly.
.mp3 — these files started the current digital music revolution. Songs can be saved in near CD sound quality and they are compact, thus easy to share (much to the chagrin of the RIAA).
.mpg — usually MPEG-4 Video (MP3’s big brother)
.ra /.rm — RealAudio/RealMedia (RealOne Player)
.mov — Quicktime Movie File
.asf — Active Streaming File. A Windows Media Audio or Video stream.
.avi — Audio Video Interleaved. A Microsoft multimedia format used for Windows Video clips.
.wma — Windows Media Audio File
.wmv — Windows Media Video file
.ogg — Ogg Vorbis  is a completely open, patent-free, professional audio encoding and streaming technology. It compresses to an even smaller size than MP3 without loss of quality. It was officially released July 2002 but it hasn’t quite caught on.
There are many players that can be used to encode and play these file types. These are my favorites based on features and functionality:
MusicMatch Jukebox — My personal favorite. Nice GUI and easy to use controls. I can tag (add song info) my music files and create playlists. What I like best is that I can use it to convert my WAV files into mp3.
Jet Audio – What I like best about this one is that I can play all my media files whether mp3, wma, RealMedia, or OGG Vorbis. It also allows the user to slow down, speed up, and add effects to a song so you don’t just listen, but interact as well.
Windows Media Player — Often ignored since it comes standard with Windows, but it’s not a bad little player. If you just want to listen to mp3 and burn the occasional CD, then you already have a good tool “bundled” with Windows. The new Media Player 10 is even better, but only works with Win XP.
WinAmp — A favorite music player with many users. Many cool effects and features can be downloaded from the web to make it even better.
RealOne Player — A necessity for playing most streaming content that has a .ra or .rm file extension.
Quicktime – Many movie trailers open in this format. IE and NS both have QT plug ins so that the clips play right in your browser.
You can head on over to the individual sites for all these players and compare features yourself. They all offer free downloads, however, some of them (like RealOne) make it harder to find the free download version.
Enjoy the music.