The Apple iPod Nano 4th Generation (also referred to as "iPod Nano 4G" and "iPod Nano Chromatic") can be distinguished from previous iPod Nano models by its taller screen, curved surface, oval shape when seen from the top or bottom, and the inclusion of an accelerometer that is used by the Shake feature. Introduced: September 2008.
The Apple iPod Nano 3rd Generation (also referred to as "iPod Nano 3G") can be distinguished from previous iPod Nano models by its wider screen, smaller square-shaped body, hold switch location on the bottom, and its ability to play video. You can also distinguish the 3rd Generation Apple iPod Nano by the last three digits of the serial number: it will be one of the following: YOP, YOR, YXR, YXT, YXV, YXX. Introduced: September 2007.
The Apple iPod Nano 2nd Generation (also referred to as "iPod Nano 2G") can be distinguished from the previous iPod Nano model by its smaller size, its colors, and that the dock connector and headphones port are both located on the bottom of the unit. You can also distinguish the 2nd Generation Apple iPod Nano from the 1st Generation model by the absence of the rounded corners and the introduction of curved sides. Introduced: September 2006.
The Apple iPod Nano 1st Generation (also referred to as "iPod Nano 1G") is the first of Apple's iPod Nano series. This iPod Nano is smaller than the iPod Mini and has a color screen and a Click Wheel but has flash memory instead of a hard drive. Song and photo syncing only occurs over USB 2 (not FireWire), and this iPod Nano comes in white and black. The capacity of the iPod Nano is engraved on the back of the case (1 GB, 2 GB, or 4 GB). Introduced: September 2005.
