The original iPod works only on the MAC OS operating system, as Windows compatibility was added from the second generation. Unlike most media players, the iPod does not support Microsoft's WMA media format, but it can be converted into a supported format with the conversion tool added in the Windows version of iTunes. Other formats like Ogg Vorbis or FLAC are not supported without installing a proper firmware first. During installation, the iPod is associated with a host computer, and each time it connects to that host computer, it can synchronize music libraries and playlists.
One can access, add, and play music from another computer (other than the host) if the iPod is set on manual and not automatic sync., but any changes made will be reversed when connecting the media player to the host computer. Songs can be rated on the iPod via iTunes. If you want to completely sync. the media library on your iPod with the one on your PC, the one on the iPod will be completely replaced with the one on the PC.
iPods with color displays use anti-aliased text and graphics, and sliding animations. All iPod models except the third generation iPod Shuffle and the iPod Touch have five buttons, and later models have their buttons implemented in the click wheel.The click wheel is an innovation from Apple which consists in the buttons not being on top of the wheel, but under it, and one must use physical power and push inwards the edge of the wheel, over the label of the desired button. The buttons on the click wheel perform basic media player tasks such as play, pause, menu, next track, previous track, fast forward and fast backward.
The third generation iPod Shuffle has no buttons on the actual device, but, however, has the basic play/pause, next/previous and volume up/down buttons on the earphone cable. The iPod Touch has no click wheel as well, as it is controlled by its 3.5 inch touch screen. The iPod Touch has few physical buttons, like the Home button, or the Awake/Sleep button. Depending on its generation, an iPod Touch can have the volume keys as one or two switches. The iPod Touch is almost identical to the iPhone, lacking however some of the iPhone's features, like calling ability. Both devices use Apple's iOS operating system.