
In April 2003, version 4.0 introduced the iTunes Store in October, version 4.1 added support for Microsoft Windows 2000 and Windows XP.

Version 3 dropped Mac OS 9 support but added smart playlists and a ratings system. Release 2.0 added support for the new iPod.

Originally a Mac OS 9-only application, iTunes began to support Mac OS X with the release of version 1.1 in March 2001. Casady & Greene ceased distribution of SoundJam MP on June 1, 2001, at the request of the developers. Macintosh users immediately began poking through iTunes's resource fork, where they discovered numerous strings and other resources that indicated that iTunes was a re-engineered Sound Jam MP. Īpple released version 1.0 of the program under a new name "iTunes" on January 9, 2001, at Macworld San Francisco. At Apple, the developers simplified SoundJam's user interface, added the ability to burn CDs, and removed the program's recording feature and skin support. At the time of the purchase, Kincaid, Jeff Robbin and Dave Heller left Casady & Greene to continue development of the program as Apple employees.

Apple purchased the program from Casady & Greene in 2000. Apple based the initial release of iTunes on SoundJam MP, a program developed by Bill Kincaid and released by Casady & Greene in 1999.
