The iPod is a portable media player developed by Apple. It is nearly ubiquitous in the portable media player market, and is often synonymous with the category.
First released in October of 2001, the iPod has quickly become one of the best selling electronics products of all time. It currently holds over 90% market share, and has sold over 297 million units worldwide.
The key design features of the iPod are its simple interface and stylish aesthetics. Most models feature a small screen, with either "scroll wheel" interface, or a touchscreen. The smallest models have no screen.
Storage sizes range from a few gigabytes to over 160 gigabytes. Most models use flash memory for storage, while the largest sizes still rely on small hard drives.
The current lineup of iPod devices are:
shuffle: tiny player with no screen
nano: slightly larger than shuffle, 1.54-inch touchscreen
classic: a hard-drive based iPod with the most storage.
touch: effectively an iPhone without the phone, 3.5-inch touchscreen
The iPhone is an iPod that's also a cell-phone.
The iPad is an oversized iPod that's a tablet computer.
A vast number of companies make products designed to work with the iPod, including docks and headphones. Most receivers and many TVs will now plug into the iPod directly to playback music and video.
The iPod is managed using Apple's iTunes software.