iPods with color displays use anti-aliased graphics and text, with sliding animations. Classic iPods have five buttons and the later generations have the buttons integrated into the click wheel — an innovation which gives an uncluttered, minimalist interface. The buttons perform basic functions such as play, next track, etc. Other operations such as scrolling through menu items and controlling the volume are performed by using the click wheel in a rotational manner. iPod shuffle does not have a click wheel and instead has five buttons positioned differently from the larger models. iPod touch uses no buttons for any of these functions, instead relying on the same Multi-touch input style as the iPhone.

iPod iTunes Store

The iTunes Store is an online media store run by Apple and accessed via iTunes. It was introduced on April 29, 2003 and it sells individual songs, with typical prices being US $0.99, AU $1.69 (inc. GST), NZ $1.79 (inc. GST), €0.99 (inc. VAT), or £0.79 (inc. VAT) per song. Since no other portable player supports the DRM used, only iPods can play protected content from the iTunes store. The store became the market leader soon after its launch and Apple announced the sale of videos through the store on October 12, 2005. Full-length movies became available on September 12, 2006.

Purchased audio files use the AAC format with added encryption. The encryption is based on the FairPlay DRM system. Up to five authorized computers and an unlimited number of iPods can play the files. Burning the files onto an audio CD, then re-compressing can create music files without the DRM, although this results in reduced quality. The DRM can also be removed using third-party software. However, in a deal with Apple, EMI began selling DRM-free, higher-quality songs on the iTunes Stores, in a category called "iTunes Plus." While individual songs were made available at a cost of US$1.29, 30¢ more than the cost of a regular DRM song, entire albums were available for the same price, US$9.99, as DRM encoded albums. On October 17, 2007, Apple lowered the cost of individual iTunes Plus songs to US$.99 per song, the same as DRM encoded tracks.

iPods cannot play music files from competing music stores that use rival-DRM technologies like Microsoft's protected WMA or RealNetworks' Helix DRM. Example stores include Napster and MSN Music. RealNetworks claims that Apple is creating problems for itself by using FairPlay to lock users into using the iTunes Store. Steve Jobs has stated that Apple makes little profit from song sales, although Apple uses the store to promote iPod sales. However, iPods can also play music files from online stores that do not use DRM, such as eMusic or Amie Street.

On July 3, 2007, Universal Music Group decided not to renew their contract with the iTunes music store. Universal will now supply iTunes in an 'at will' capacity.

On September 5, 2007, at Apple's Media Event entitled "The Beat Goes On...", the company debuted the iTunes Wi-Fi Music Store which allows one to access the Music Store from either iPhone or the new WiFi-enabled iPod Touch and download songs directly to the device. When you next sync the device with iTunes, any purchased music is copied onto your iTunes Library.

File Storage and Transfer

With the exception of the iPod touch, all iPods can function as mass storage devices to store data files. If the iPod is formatted on a Mac OS X computer it uses the HFS+ file system format, which allows it to serve as a boot disk for a Mac computer. If it is formatted on Windows, the FAT32 format is used. With the advent of the Windows-compatible iPod, iPod's default file system switched from HFS+ to FAT32, although it can be reformatted to either filesystem (excluding the iPod shuffle which is strictly FAT32). Generally, if a new iPod (excluding the iPod shuffle) is initially plugged into a computer running Windows, it will be formatted with FAT32, and if initially plugged into a Mac running Mac OS X it will be formatted with HFS+.

Unlike many other MP3 players, simply copying audio or video files to the drive with a typical file management application will not allow iPod to properly access them. The user must use software that has been specifically designed to transfer media files to iPods, so that the files are playable and viewable. Aside from iTunes, several alternative third-party applications are available on a number of different platforms.

iTunes 7 and above can transfer purchased media of the iTunes Store from an iPod to a computer, provided that the DRM media is transferred to any of the five computers allowed for authorization with DRM media.

Media files are stored on the iPod in a hidden folder, together with a proprietary database file. The hidden content can be accessed on the host operating system by enabling hidden files to be shown. The audio can then be recovered manually by dragging the files or folders onto the iTunes Library or by using third-party software.

( Information Source: Wikipedia )