The 4th Generation iPod touch, shown in the diagram above, introduced a number of major improvements to the device. While it doesn't have as many ports and buttons as the iPhone, it's still got a lot of hardware features to learn about. Knowing what each one does will help you get the most out of your iPod touch.
The 4th Generation iPod touch is no longer produced. The current model is the 7th Generation iPod touch.
There are a number of other interesting hardware features of the iPod touch that are worth knowing. They're not shown in the picture above because they're internal to the device.