1st Generation

• The first-generation iPod touch 16GB can contain up to 3,500 songs in 128 Kbps Advanced Audio Coding format, 20,000 photos and 20 hours of video. Providing twice as much flash memory, its 32GB counterpart consequently doubles the aforementioned numbers apart from picture capability: 7,000 numbers, 25,000 photos and 40 hours of video. The first-generation models were released in September 2007.
  
  

2nd Generation

• The 2G iPod touch 16GB and 32GB, released in September 2008, retain the same capacities as the previous production cycle. However, the device's battery life is increased from 22 hours of audio playback and five hours of video playback to 36 hours and six hours, respectively. Also, although the iPod touch has the same 4.3-inch height and 2.4-inch width, its depth is increased from 0.31 inches to 0.33 inches and weight reduced from 4.2 oz. to 4.1 oz.
  
  

3rd Generation

• Apple discontinued the iPod touch 16GB with the third generation of production. The surviving iPod touch 32GB, released in September 2009, has the same song and video capacities. However, the maximum amount of pictures it can hold is increased from 25,000 to 40,000. Also, audio playback is reduced from 36 hours to 30 hours.
  
  

4th Generation

• The iPod touch 32GB carries, released in September 2010, over the same capacity from the third generation into the fourth -- and at the time of publication, current -- production cycle. Still, the 4G iPod touch represents the greatest amount of change made to the media player. Audio and video playback is bumped up to 40 hours and seven hours, respectively. It is also slightly smaller in size, with a weight of 3.6 oz.. Bluetooth wireless connectivity was added for this production cycle.