The Original iPhone

• Confusingly, the first generation iPhone was called the iPhone 2G. Apple released this model in 2007 and revolutionized the cellphone industry. Suddenly, a phone was a Web browser and mini computer, capable of downloading applications and sending texts at the same time, but also of taking videos and photos while playing music. The iPhone 2G had a 3.5-inch touch-screen display and a 2-megapixel camera.
  
  

iPhone 3G

• The iPhone 3G followed a year and a couple of months behind the 2G and offered few notable upgrades over the previous version. The phone still came in two different capacities -- 8GB and 16GB -- but with a color choice in the 16GB version between white and black. The 3G phone was a 0.1 oz. lighter than the 2G but had a lot of the same guts -- the same camera, same Wi-Fi capabilities and battery life. The 3G added assisted GPS, however, bringing navigation into your pocket.
  
  

iPhone 4G

• Apple released the iPhone 4G early in 2010 with a significant range of improvements over the previous two versions. Outwardly, the phone remained mostly the same, without notable changes to its dimensions or weight. On the inside, however, the iPhone 4G was reborn. Apple reworked the W-iFi card to include n-band broadcasts, speeding up the Internet when using the iPhone on a local network. The capacity was doubled, with 16GB and 32GB versions of the 4G. The cameras were doubled too: Apple added a front-facing camera for use with FaceTime -- a video chat program -- and improved the internal camera to take HD videos up to 720p.
  
  

Battery Life

• According to Apple's technical specifications for the devices, all models of the iPhone have about 250 hours of battery life on standby, up to 14 hours of talk time, 40 hours of video playback and 10 hours of audio playback before charging.