The iPhone 4 was released by Apple in June 2010, marking a significant upgrade from its predecessor, the iPhone 3GS. It featured a sleek design with a glass front and back, a 3.5-inch Retina display, and a front-facing camera for video calls. The device was powered by the A4 chip, which improved performance and battery life. The iPhone 4 introduced the iOS 4 operating system, allowing users to multitask between applications. It also included a 5-megapixel rear camera with LED flash, enhancing photo quality. This model was pivotal in establishing the smartphone's popularity and set the stage for future innovations.