Ipod

iPod is a brand of portable media players that is designed and marketed by Apple. Since October 2004, iPod sales have dominated the market for digital music players in the United States. Devices in the iPod range are primarily digital music players, designed around a central click wheel — although the iPod shuffle has buttons only. The full-sized model stores media on an internal hard drive, while the smaller iPod nano and iPod shuffle use flash memory. Like many digital audio players, iPods can also serve as external data storage devices.
In addition to playing music, iPods with display screens can display calendars, contact information, and text files, and play a limited range of games. Models introduced in 2004 include the ability to display photos and the fifth-generation iPod, introduced in 2005, can additionally play video files. In January 2007, Apple announced the iPhone, combining the features of a video-capable iPod with integrated mobile phone and mobile internet capabilities.
Apple's iTunes software is used for transferring music (as well as photos, videos, games, contacts and calendars, for models that support those features). As a free jukebox application, iTunes stores a comprehensive library of music on the user's computer and can play, burn, and rip music from a CD. It can also sync photos and videos.
Apple focused its development on the iPod's unique user interface and its ease of use, rather than on technical capability. The iPod is currently the world's best-selling range of digital audio players and its worldwide mainstream adoption makes it one of the most popular consumer brands. Some of Apple's design choices and proprietary actions have, however, led to criticism and legal battles.

Battery life
For example, the fifth generation 30 GB iPod is advertised as having up to 14 hours of music playback.

iPod batteries are not designed to be removed or replaced by the user. Some iPod users have been able to open the iPod case themselves, usually following instructions provided by third-party vendors of iPod replacement batteries. However, the procedure can be tricky, and is poorly suited for people who are uncomfortable working with electronic components. Compounding this problem, Apple initially would not replace worn-out batteries. The official policy was that the customer should buy a refurbished replacement iPod, at a cost almost equivalent to a brand new one. All lithium-ion batteries eventually lose capacity during their lifetime and this situation led to a small market for third-party battery replacement kits.