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 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 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 ARMv4 platforms, with earlier iPods making use of the PortalPlayer PP50xx series of systems-on-a-chip, and later iPods switching to Samsung Electronics S5L84xx and S5L87xx SoCs similar to those used in early iOS devices. The iPod shuffle (1st generation) is unique in using a SigmaTel STMP 3550 processor, based on the Motorola 56000 digital signal processor instruction set.

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 GB in 2007. iPod shuffle was the first iPod to bring flash memory to the lineup, although at much smaller capacities - 4 GB 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 GB as the most premium storage option in 2008. The iPod touch provided up to 32 GB in 2007, reaching 256 GB 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, iPod nano (7th generation), 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 nano (7th generation) and iPod touch (5th generation) use Lightning.

iPods initially received firmware updates by using the iPod Updater utility from a computer. With iTunes 7.0, the IPSW file format was introduced to allow iTunes to update and restore iPods. 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, making use of hard drive storage.
 * iPod Photo: A variant of the iPod with Click Wheel (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 miniaturized iPod designs, making use of flash storage.
 * iPod mini: Short-lived predecessor to the iPod nano, making use of hard drive storage.
 * iPod shuffle: Experimental iPod designs with no display, sometimes with no buttons, making use of flash storage.
 * iPod touch: Wi-Fi-only variant of the iPhone, unique in the iPod product line for running iOS.

Partnerships
Apple released iPod products under various partnerships. Special edition iPods branded in the style of various artists were released across the iPod's lifetime. The most prominent of these partnerships are highlighted below.

U2
Apple released some iPod models in U2 Special Editions. These iPods featured a front design in black with red click wheel in the style of the How to Dismantle an Atomic Bomb album cover, and laser-etched signatures of the band members on the rear cover, in addition to "U2 Special Edition" labeling. The iPod (4th generation) U2 Special Edition was released on 2004, ahead of the album release on 2004. The promotion was later extended, with further iPods receiving identical U2 Special Edition designs.

The devices released under this partnership were:


 * iPod with Click Wheel (4th generation) U2 Special Edition
 * iPod with Color Display (iPod Photo) U2 Special Edition
 * iPod with video (5th generation) (Original and Rev A) U2 Special Edition

Product Red
Apple partnered with Product Red numerous times to sell special edition iPods in a red finish, exclusively through the Apple retail and online stores. Product Red is a brand of ONE Campaign, a non-profit advocacy organization co-founded by U2 lead vocalist Bono alongside Bobby Shriver. A portion of revenue from sales is donated to The Global Fund to Fight AIDS, Tuberculosis and Malaria.

The devices released under this partnership were:


 * iPod nano (2nd generation) PRODUCT(RED) Special Edition (4 GB/8 GB)
 * iPod shuffle (2nd generation) PRODUCT(RED) Special Edition (1 GB/2 GB)
 * iPod nano (3rd generation) PRODUCT(RED) Special Edition (8 GB)
 * iPod nano (4th, 5th, 6th, and 7th generations) PRODUCT(RED) Special Edition (8 GB/16 GB)
 * iPod shuffle (4th generation) PRODUCT(RED) Special Edition (2 GB)
 * iPod touch (5th generation) PRODUCT(RED) Special Edition (16 GB/32 GB/64 GB)
 * iPod touch (6th generation) PRODUCT(RED) Special Edition (16 GB/32 GB/64 GB/128 GB)
 * iPod touch (7th generation) PRODUCT(RED) Special Edition (32 GB/128 GB/256 GB)

The partnership has continued beyond the iPod era, with iPhones, Apple Watches, and case/band accessories also receiving Product Red special editions.

iPod+HP
Announced on 2004 at the Consumer Electronics Show, Hewlett-Packard partnered with Apple to release iPods co-branded with the HP logo, and to preinstall iTunes on their consumer HP Pavilion and Compaq Presario computers.

The Apple/HP co-branded devices released under this deal were:

An iPod (3rd generation) with HP's blue brand color front plate design was demonstrated by HP CEO Carly Fiorina at the CES presentation, however, it was never sold.

HP variants of these devices were manufactured by Apple and were identical in both hardware and software, but were sold in HP packaging, and used HP model and serial numbers. Customer support, including warranty claims, were to be directed to HP's customer service channels, rather than AppleCare. The included CD only includes an installer for iTunes for Windows, not macOS. Still, being completely standard iPods in software, they could be used with a Mac, which would reformat the iPod as HFS+.

HP additionally sold vinyl skin wraps for the iPod (4th generation) and iPod mini, named "HP iPod Printable Tattoos". Skins were made available with designs including those of Ashlee Simpson, The Cure, Gwen Stefani, The Hives, Keane, Lloyd Banks from G-Unit, Vanessa Carlton, and The Who. A blank skin template was also sold, allowing the user to create and print their own design using an inkjet printer.

The partnership was terminated by HP on 2005, after Fiorina was replaced by new CEO Mark Hurd. HP+iPod sales ceased in 2005. However, HP were still prevented from releasing a competing MP3 player device until 2006. iTunes continued to be preinstalled on HP computers until a partnership with RealNetworks Rhapsody was announced on 2006.

The partnership has been criticized for being made with poor negotiation and strategy on HP's part. While HP received the ability to sell the iPod product which at this point was growing in popularity, especially with Windows users, Apple had the upper hand in receiving additional advertising for the iTunes Store via HP's computers, additionally putting HP in a position that they would not be able to advertise competitors such as Microsoft's MSN Music. In addition, HP+iPod models were sold in HP's retail channels, while Apple was in the process of making distribution deals with similar retailers. After only 2 months of the delayed release of HP's iPod (4th generation), Apple released the iPod Photo, which took a further 5 months to be released in the HP+iPod product line. It has been reported that the peak of the HP+iPod partnership only represented 5% of all iPod sales.

Avon
In 2009, a special Gold edition of the 1 GB iPod shuffle (2nd generation) was sold via an Avon promotion. It was sold through various promotions, where the customer would purchase an amount of products from the store to receive a complimentary iPod. Unlike the iPod+HP partnership, Avon makes clear in included documentation that Apple covers the iPod's warranty. In addition to the customer promotion, Avon dealers received an iPod shuffle with Avon logo branding. Customer iPods did not have additional branding.

Battery aging
With all iPods being anywhere between and  years old, having significantly fallen out of favor to smartphones that are more powerful and capable of music streaming, issues related to lithium-ion battery aging are likely to appear. Batteries that have been drained for many years tend to develop problems with reporting accurate battery charge percentage, which can lead to the device failing to charge, or unexpectedly powering off.

Cells in aged batteries tend to expand when they fail. The unibody design of many iPods, and the very tight tolerances used to secure the front and back case together on other iPods, pose a risk for the aged batteries. This is known in the community as "the spot", because many iPods were designed with the battery behind the LCD, causing the failure to present itself through a visible pressure point in the center of the LCD. The extremely thin designs used by most iPod nanos present the risk of puncturing the battery while attempting to remove it from the case, which can release toxic chemicals and potentially start a fire.

2005 iPod battery life class action
On 2005, Apple proposed a settlement of class action regarding iPods exhibiting reduced battery life as compared to Apple's advertised battery lifetime ratings. Customers in the United States who purchased or obtained a 1st, 2nd, or 3rd generation iPod prior to 2004 were eligible to receive Apple Store credit worth US$50, a free repair or replaced iPod (if the customer purchased an iPod with dock connector (3rd generation)), a check worth US$25 (in the case of an earlier iPod), or 50% compensation for a prior battery or full device replacement made at the customer's cost. The deadline to claim the offer was the later of 2005, or two years from the original purchase date. The corresponding replacement program continued until 2006.

iPod nano (1st generation) battery safety risk
On 2011, Apple issued the iPod nano Replacement Program recall, because "the battery in the iPod nano (1st generation) may overheat and pose a safety risk". It is speculated that the root cause is battery expansion pushing against the click wheel, which is not able to spread the load as other iPods are able to, where the battery is behind the display. The program exchanged any iPod nano (1st generation) with the latest generation of iPod nano available at the time, and ended sometime prior to 2017.