Audion supports three different types of audio in one application:

MP3 files

MP3 is a method of compressing audio to save space: MP3 files smooth portions of audio frequencies that you aren't likely to hear, vastly saving space. A song that could've previously taken 50 megabytes of your hard disk space takes up about 5 megabytes when compressed in MP3 format. As a result, MP3 files are very popular as they are easily downloadable over the Internet, and offer near CD-quality sound!

Network (streaming) audio

Network audio sends your computer a constant stream of MP3 data. It's basically the Internet equivalent of a radio station; you tune in, and listen to someone else's broadcast. These streams, such as Shoutcast or Icecast streams, are really just big MP3 files that are played as they're downloaded, which means you don't have to wait for a file to completely download to start enjoying your music! There are a number of network audio streams on the 'net, and since anyone can set up a station, there's bound to be even more as time goes by.

CD's

You're probably already familiar with the CD (compact disc): it's shiny, it's rather tiny, and it's packed with up to 74 minutes of audio! Compact discs offer the highest quality sound with no compression (and, as a result, pristine audio), but you can't easily send a CD over the Internet! If you're not familiar with a CD, then we'd like to welcome you to the year 1999 and we'd like to see your time machine, if at all possible.