The iPhone (commonly known as the "iPhone 2G") was Apple's first smartphone. It was announced on and released on .
The iPhone used many "off the shelf" components
When announced and released, the iPhone 2G was simply called iPhone. However, with the release of the iPhone 3G in , the original iPhone became commonly known as the "iPhone 2G." The reasoning is believed to be two-fold: it is the iPhone preceding the "3G" (and 2 is one before 3), and it only supported GSM and EDGE networks (commonly called "2G" networks).
Naturally, as a first generation device, the original iPhone is one of the more "hack-friendly" iDevices. Within two months of its release, geohot (George Hotz) "unlocked" the AT&T only phone to work on T-Mobile. A few months later, the iPhone Dev Team discovered "Pwnage," a bootrom level untethered exploit that allowed jailbreaking the device on any version of iPhone OS.