When was the first iPhone released?

Jobs introduced the iPhone at the Macworld conference in San Francisco as three devices in one: an iPod, a phone and an internet communicator. It replaced physical keyboards with a large multi-touch screen, which was unusual for phones at the time. The original model came in 4 GB and 8 GB versions priced at 499 and 599 dollars, and it worked only on the AT&T network in the US. It lacked an app store, which arrived a year later in July 2008 with the iPhone 3G. The iPhone went on to become one of the best-selling products in history, with more than 2 billion units sold.