The Apple Inc. iPhone 4 introduced significant changes and upgrades over its predecessor, the iPhone 3GS, setting a new standard in smartphone design and functionality. One of the most noticeable changes is the sleek new design featuring a glass front and back, along with a stainless steel frame that not only enhances aesthetics but also improves durability. The new design results in a thinner profile, making the iPhone 4 one of the slimmest smartphones on the market at its launch.The iPhone 4 also boasts a Retina display, providing a resolution of 960 by 640 pixels. This revolutionary display offers four times the pixel density of the iPhone 3GS, resulting in sharper text, more vibrant colors, and an overall enhanced visual experience. In terms of performance, the iPhone 4 is powered by the A4 chip, which delivers faster processing speeds and improved graphics performance compared to the 3GS's chip. This translates into quicker app launches, smoother multitasking, and an overall more responsive user experience.The iPhone 4 introduced a front-facing camera, enabling users to engage in FaceTime video calls, a feature that revolutionized communication among Apple users. The rear camera was upgraded to 5 megapixels and incorporated advanced features such as LED flash and the ability to record high-definition 720p video at 30 frames per second, marking a significant leap in mobile photography and videography.Additionally, the iPhone 4 introduced improved battery life, allowing for extended usage on a single charge, making it more convenient for everyday use. Another pivotal enhancement was the inclusion of iOS 4, which introduced multitasking capabilities, allowing users to switch between apps seamlessly. This update also brought features such as folders for organizing apps and an upgraded mail app, enhancing the overall functionality of the device.With these advancements, the iPhone 4 established itself not just as a successor to the iPhone 3GS, but as a transformative device in the smartphone industry, combining innovation, performance, and design in a way that set the stage for future iterations of the iPhone.