Throughout most of the history of recorded sound, the traditional method for distributing and accessing recordings has been a physical object--a cylinder, a disc, a reel of tape, a cassette. During the first two decades following the introduction of digital audio technology, this tradition continued with the development of several physical formats for digital audio data: the compact disc, digital audio tape, and the minidisc.
Digital audio technology is quickly moving away from traditional physical distribution to network distribution. Although network distribution has been available for well over a decade, it was only with the introduction of digital audio players in 1998 and Napster in 1999 that digital audio files were commonly distributed over networks without the use of physical media, other than the hard drive of the destination computer. Most industry observers predict that physical distribution of sound recordings will eventually be abandoned altogether.
In this section, we will look at the four most common ways that digital audio files are distributed from one computer to another over networks: making them available on servers for downloading, streaming them in real time, sharing them over peer-to-peer networks, and syndicating them as a podcasts.