digital media player application created by Apple in 2001. iTunes was at the forefront of the digital music revolution, providing a free, user-friendly means to play and organize digital music and video files. iTunes was developed as a complete work, with nonstandard interfaces that are independent of the host operating system (OS), inverting the typical hardware/OS/application relationship.

Songs stored on iTunes can be organized across a range of detailed information, allowing the user to search under a variety of headings, including artist, album, song, or genre. It also contains functions that allow the user to create various playlists, create CDs, or listen to songs most recently added to the user's library. Additionally, iTunes plays streaming audio from the Internet, connecting listeners to radio stations around the world.

Compatible with both Mac and PC systems, iTunes is an interface to manage Apple's popular iPod (mp3 player) and the iPhone. Since its beginnings as a digital music library, iTunes has developed many additional features. For instance, in 2003 Apple launched the iTunes Store, which gave users the ability to purchase and download music from the Internet directly to their iTunes library. By July 2007 the store had sold more than 3 billion songs. In addition to music, the iTunes Store also offers music videos, television shows, games, podcasts (broadcasts transmitted by and through iPods), and feature-length films for download.