iTunes is a music application created by Apple for Macintosh and Microsoft Windows computers. The program allows users of Mac OS 9, Mac OS X, Windows 2000, or Windows XP to manipulate digital music they own. Users are able to organize playlists, edit ID3 tags, burn compact discs, upload to MP3 players, and run a visualizer to display the music in a psychedelic, visual form. The primary export formats are AAC and MP3.
iTunes is available as a free download for Mac OS X, Windows Vista, and Windows XP from Apple's website. It is also bundled with all Macs, and some HP and Dell computers. Older versions are available for Mac OS 9, OS X 10.0-10.2, and Windows 2000. Although Apple does not produce iTunes for other operating systems, it can be run on Linux-based operating systems through Wine, a Windows compatibility layer.
Sharing songs via a network can be done automatically. Shared lists of songs within the same subset are automatically detected, while shared lists outside of the subset can be added by specifing an IP address. The original version of iTunes supported sharing over any network (including the Internet). This was disabled when people started using it in ways that Apple considered to violate their End User License Agreement. Specifically, their concern was targeted at a music-sharing effort called iCommune. (iCommune said and continues to say it did not intend to go afoul of either the contractual agreements, or copyright law.)
iTunes Library songs can be shared over a local network using Bonjour (formerly Rendezvous)—Apple's implementation of the Zeroconf (zero configuration required) open network standard—which allows shared lists of songs within the same subnet to be automatically detected. When a song is shared, iTunes can stream the song but won't save it on the local hard drive, in order to prevent piracy. Songs in Protected AAC format can also be accessed but authentication is required.
Originally with iTunes 4.0, users could freely access shared music anywhere over the internet, in addition to one's own subnet, by specifying IP addresses of remote shared song libraries. Apple quickly removed this feature with version 4.0.1, claiming that users were violating the EULA.
Music sharing uses the Digital Audio Access Protocol (DAAP), created by Apple for this purpose. [2] DAAP has been reverse-engineered and is now used to stream playlists from non-Apple software.
Just days after the Windows version of iTunes was released, William Zeller, a 20-year-old Trinity College student, wrote myTunes, a program which allows Windows users to circumvent the iTunes restriction and download music from an iTunes shared playlist over a network. MyTunes quickly became popular and is now widely used. There also exists a similar open source Java client, called ourTunes.