Can't tell which generation iPod nano you have? Here's the evolution of Apple's tiny music player.
The first generation iPod nanos came in black and white.
iPod nano - 2nd generation
The second generation iPod nano is smaller than the original and came in five colors. There was also a Product (RED) special edition available, in addition to the original colors.
iPod nano - 3rd generation
The third generation iPod nano had a wider screen and was able to play video.
iPod nano - 4th generation
The fourth generation iPod nano was taller with a curved body. It was available in nine colors.
iPod nano - 5th generation
The fifth generation iPod nano was taller than the previous version and featured a camera and microphone.
iPod nano - 6th generation
The sixth generation iPod nano was chopped down to a watch-sized music player.