Time Frame

• Apple released its second-generation iPod in July 2002. The third-generation iPod (dock connector) replaced it in September 2003.
  
  

The Touch Wheel

• The first-generation iPod uses a turn wheel that physically turns to enable users to navigate its menus. The second-generation iPod introduced the touch wheel, which is fixed to the unit and does not move. Users navigate the menus by touching the wheel.
  
  

Memory

• The second-generation iPod was available in three different storage capacities: 5 GB, 10GB and 20GB. That amount of memory allows users to store up to 1,000, 2,000 and 4,000 songs, respectively.
  
  

Size

• The three touch wheel models vary slight in size. Each is 4 inches high and 2.4 inches wide. The 5GB model is 0.78 inches deep, the 10GB is 0.72 inches deep, and the 20GB model is 0.84 inches deep. The 5GB and 10GB models each weighs 6.5 oz., and the 20GB model weighs 7.2 oz.