The original iPhone was officially announced on January 9, 2007, and was released on June 29, 2007. The original iPhone was available in 4, and 8 GB capacities, with a 16 GB capacity released on February 5, 2008. Soon after the original release, Apple dropped iPhone prices by $100. As a concession to early adopters (after criticism), Apple offered a $100 store credit. I used my store credit to purchase the $99 Apple Bluetooth Headset.
The original iPhone introduced the “multi-touch” display that allowed control by dragging one or more fingers across the glass display, although no interface controls required multiple fingers in the iPhone OS 1.0. This iPhone has sensors including an accelerometer (to detect landscape or portrait orientation), an ambient light sensor (to control screen brightness), and a proximity sensor (to turn off the display when held to the ear).
Other features include Wi-Fi (802.11b/g), EDGE, Bluetooth 2.0, and a 2.0 megapixel camera. The case is 2.4 inches by 4.5 inches, is 0.46-inch thick, and weighs 4.8 ounces.
Source: EveryMac.com and AppleInsider.