Though the iPod was released in 2001, its high price and Mac-only availability caused sales to be relatively slow until 2004 when iTunes was released for Windows. iPods with color displays use anti-aliased graphics and text, with sliding animations. All iPods (except the 3rd-generation iPod Shuffle, the 6th generation iPod Nano, and iPod Touch) have five buttons and the later generations have the buttons integrated into the click wheel– an innovation that gives an uncluttered, minimalist interface. The buttons perform basic functions such as menu, play, pause, next track, and previous track. Other operations, such as scrolling through menu items and controlling the volume, are performed by using the click wheel in a rotational manner. The 3rd-generation iPod Shuffle does not have any controls on the actual player; instead it has a small control on the earphone cable, with volume-up and -down buttons and a single button for play and pause, next track, etc. The iPod Touch has no click-wheel; instead it uses a 3.5" touch screen along with a home button, sleep/wake button and (on the second and third generations of the iPod Touch) volume-up and -down buttons. The user interface for the iPod Touch is identical to that of the iPhone. Differences include a lack of a phone application. Both devices use iOS.