IPod

The iPod was a line of portable media players released by Apple between 2001 and 2019. Three major iPod product lines were released making use of the iPod operating system, while the iPod touch ran iOS. On 2022, Apple announced the retirement of the iPod product line.

With some unique exceptions, the iPod product line makes use of a "click wheel", a plastic dial that is touch-sensitive. The user rotates their finger clockwise or counter-clockwise to navigate through lists on the device, or to adjust volume. The user can then click the center button to select an item, or click a navigational button: Menu, Play/Pause, Previous Song, and Next Song. Earlier variations of the iPod classic use a mechanically rotating wheel, with navigational buttons either on the outside of the wheel, or in a row above it. Later iPod nanos, and all iPod touches, make use of a touch screen rather than a click wheel. iPod shuffles provide few or no buttons, and no display, instead opting to provide a simplified set of playback options based around shuffling songs in a library.

While later iPod software uses of iOS-inspired design elements, no iPod (other than iPod touch) runs iOS - rather, they are based on the Pixo OS product Apple acquired from Pixo. However, iPods launched in 2006 and later do make use of iBoot as their bootloader. All iPods are based on the ARMv6 platform, with earlier iPods making use of the PortalPlayer PP5000 series of systems-on-a-chip, and later iPods switching to Samsung S5L87xx SoCs similar to those used in early iOS devices. The iPod shuffle (1st generation) is unique in using a SigmaTel STMP 3550 processor.

The iPod classic and iPod mini product lines make use of a compact hard drive for storage, enabling them to hold significant capacity at a low cost - reaching 160 GiB in 2007. iPod shuffle was the first iPod to bring flash memory to the iPod lineup, although at much smaller capacities - 4 GiB being the most premium storage option in 2009. The iPod nano's replacement of the iPod mini product line brought flash memory to its form factor, reaching 16 GiB as the most premium storage option in 2008. The iPod touch provided up to 32 GiB in 2007, reaching 256 GiB in 2019 as the final iPod sold.

Again excluding the iPod touch, no iPod has the capability to connect to the internet, or otherwise to use Wi-Fi. Only the iPod nano (7th generation) supports Bluetooth headphones. iPods act as a portable extension to the iTunes software, and for a brief period, Musicmatch Jukebox, provided for Windows users until iTunes was released for Windows. A user would maintain a music library in iTunes, and sync some or all of this library to their iPod over FireWire, or later USB. Some iPods can receive FM radio, using wired headphones as an antenna.

All iPod designs, with the exception of the iPod shuffle and later iPod touches, connect to a computer or accessory through the 30-pin connector. iPod shuffles initially connected through a built-in USB connector, and later via a cable that adapts the 3.5mm headphone port to USB. iPod touch (5th generation) and later use Lightning.

The iPod operating system makes use of the IPSW file format, however the structure of iPod IPSWs significantly differs from iOS IPSWs.

iPod product lines

 * iPod classic: The original iPod product line, later renamed iPod classic to differentiate it from the other product lines.
 * iPod Photo: A variant of the iPod (4th generation) with larger, full-color display.
 * iPod Video: The name given to the iPod (5th generation), having a significantly larger display for watching videos.
 * iPod nano: Product line of various miniaturised iPod designs.
 * iPod mini: Short-lived predecessor to the iPod nano.
 * iPod shuffle: Experimental iPod designs with no display, sometimes with no buttons.
 * iPod touch: Wi-Fi-only variant of the iPhone, unique in the iPod product line for running iOS.