Apple CEO Steve Jobs unveiled the first iPhone on January 9, 2007. Instead of the button-filled feature phones popular at the time, the iPhone used a giant capacitative multi-touch screen for interactions. Where popular BlackBerry devices sported a full QWERTY keyboard, the iPhone had just four buttons: two volume buttons, a ring / silent switch, and a home button.
The iPhone was initially unveiled with a plastic screen. This was changed to a glass screen ahead of the phone's launch on June 29. In 2017, Apple chief operating officer Jeff Williams described a last-minute dash to perfect the glass screen technology.
The fourth-generation iPhone was a major redesign. The volume rocker was replaced by two circular buttons, the plastics were dropped from the rear in favor of glass, and the edges used a stainless steel frame. Oh, and the white option now switched the front bezel to white as well.
Apple retained the same design for the next few years bar some minor tweaks. The iPhone 6S in 2015 used a strong 7000 series aluminum for the casing. The iPhone 7 in 2016 dropped the headphone jack, added waterproofing, and brought a dual-lens camera to the Plus model. The iPhone 8 in 2017 brought a glass casing back to the rear.
Debuting the same year as the iPhone 8 and 8 Plus, the X upended several expectations about the iPhone range. Gone was the iconic home button, replaced with a series of swiping gestures and a new face scanner. The 5.8-inch screen came in a body that measured around the same size as the iPhone 8, aided by new OLED technology.