iTunes is a media player and digital distribution marketplace developed by Apple and originally released as version 1.0 on January 9th, 2001. iTunes has two elements to it: the media player/library, and a digital distribution network run by Apple. iTunes is available for Mac OS X as well as Windows XP and Vista, and is available on the iPhone as well.

On September 9th, 2009, Apple announced iTunes 9. New features in 9.0 include Genius for playlists, the ability to manage your installed iPhone and iPod apps from within iTunes while your portable device is plugged in, a redesigned store, the option to share your media files with other computers in your home network, improved syncing including but not limited to the ability to sync by artist name or genre, and a totally revamped iTunes Store with Facebook and Twitter integration.

The most notable new feature in iTunes 9 is iTunes LP, though. Intended to simulate the now-lost experience of getting a plethora of large, attractive liner notes, artwork, and photos with old vinyl records, the iTunes LP feature includes both classic liner notes and imagery, and new, DVD special feature-esque content. Apple released iTunes 9.0.2 in late October 2009, providing further enhancements to the iTunes Music Store layout, adding support for Apple TV 3.0, and once again blocking Palm Pre syncing.

The iTunes media player is a desktop media player that supports the MP3, Apple Lossless, WAV, AAC, AIFF, and MPEG-4 formats for playback, ripping, and conversion. Songs can be sorted according to a list of attributes such as track number, song title, album, and artist, and viewed in the GUI several different ways, including the unique Cover Flow style (where the covers of albums are displayed much like a Rolodex, allowing the user to flip through them). Much like other media players such as Winamp or Windows Media Player, iTunes supports visualization as well as an equalizer to tune the sound.

Two features unique to iTunes are iPod synchronization and the Genius recommendation system. iTunes is the only media player that supports synchronization to an iPod because of Apple's usage of a hash algorithm in the synchronization process. This has brought Apple into conflict with open-source groups attempting to reverse-engineer the hash to allow synchronization for other software. Synchronization of an iPod with iTunes will cause the iPod to automatically copy new media over to the iPod each time the iPod connects to the host computer. This allows users to keep their iPod libraries up-to-date with their iTunes libraries. Currently, iTunes does not support synchronizing or copying of media not bought through the iTunes store.

The Genius recommendation system is a part of iTunes that offers feedback on songs and finds songs similar to previous songs in both the iTunes store and in the library. In this fashion it is similar to the Pandora or last.fm recommendation systems, but integrated with iTunes. Genius can recommend between 25 and 100 songs, depending on user preference.

The iTunes store is a digital distribution network that allows users to purchase albums or individual songs from a large database of content. The iTunes store also supports the rental of movies and TV shows for viewing. When a song or video is purchased, it is automatically downloaded and linked to that user, allowing them to synchronize it to their iPod. Currently, Songs are priced on a flat $0.99 for all songs. Songs will be priced on three tiers starting April 2009: $0.69, $0.99, and $1.29. The majority of songs will be $0.69 in price. Each individual song will be priced on a case-by-case basis according to how much the record label charges Apple. At MacWorld 2009 it was announced that the iTunes store is going DRM-free, with the majority of songs already DRM-free and the rest going DRM-free by the end of March 2009.