The iPhone is a line of smartphones designed and marketed by Apple Inc. It runs Apple’s iOS mobile operating system. The first generation iPhone was released on June 29, 2007; the most recent iPhones, the seventh-generation iPhone 5C and iPhone 5S, were introduced on September 10, 2013. The touchscreen on the first five generations is a 9 cm (3.5 in) liquid crystal display with scratch-resistant glass, while the one on the iPhone 5 is 4 inches. The capacitive touchscreen is designed for a bare finger, or multiple fingers for multi-touch sensing. The screens on the first three generations have a resolution of 320×480 (HVGA) at 163 ppi; those on the iPhone 4 and iPhone 4S have a resolution of 640×960 at 326 ppi, and the iPhone 5, 640×1136 at 326 ppi. The iPhone 5 model’s screen results in an aspect ratio of nearly exactly 16:9.
The touch and gesture features of the iPhone are based on technology originally developed by FingerWorks. Most gloves and styli prevent the necessary electrical conductivity; although capacitive styli can be used with iPhone’s finger-touch screen. The iPhone 3GS and later also feature a fingerprint-resistant oleophobic coating. The iPhone 4 introduced a 5.0-megapixel camera (2592×1936 pixels) that can record video at 720p resolution, considered high-definition. It also has a backside-illuminated sensor that can capture pictures in low light and an LED flash that can stay lit while recording video. It is the first iPhone that can natively do high dynamic range photography. The iPhone 4 also has a second camera on the front that can take VGA photos and record SD video. Saved recordings may be synced to the host computer, attached to email, or (where supported) sent by MMS.
The iPhone 4S’ camera can shoot 8-MP stills and 1080p video, can be accessed directly from the lock screen, and can be triggered using the volume-up button as a shutter trigger. The built-in gyroscope can stabilize the image while recording video. The iPhone 5 and iPhone 4S, running iOS 6 or later, can take panoramas using the built-in camera app, and the iPhone 5 also can take still photos while recording video. The camera on the iPhone 5 reportedly shows purple haze when the light source is just out of frame, although Consumer Reports said it “is no more prone to purple hazing on photos shot into a bright light source than its predecessor or than several Android phones with fine cameras…”