Apple's iPhone is one of the most popular smartphones in the world. The iPhone was first introduced in 2007 and is widely credited with bringing effective touchscreen technology to the mass market. However, it was not the first touchscreen smartphone.
Apple has released an iPhone every year since 2007. The company began with the original iPhone in 2007, which initially only launched in the US and was a non-3G phone. Apple introduced the iPhone as a combination of three devices: a widescreen iPod with touch controls, a mobile phone and an Internet communicator. The original iPhone initially received negative press as it had a non-removable battery, no expandable memory and was exclusively sold through US carrier AT&T.
The iPhone 3G was launched in various other worldwide markets a year later and added 3G connectivity, while the iPhone 3GS (2009) kept the same design but added a faster processor and a built-in compass.
The iPhone 4 (2010) saw a completely new design, with the antenna built into the edges of the phone and a sheet of glass on the back. The design caused some controversy when it was discovered that holding the phone in a certain position affected reception quality. Apple offered a free case to buyers that helped solve the issue.
The current iPhone 4S (2011) features an identical design to the iPhone 4 but has a faster processor, more memory and an upgraded camera.
Traditionally, Apple releases one iPhone every calendar year. The releases are timed so that previous iPhone owners who signed a two year contract can upgrade to the new and latest iPhone.