The iPhone 4S is a smartphone developed by Apple Inc., released in October 2011. It features a 3.5-inch Retina display, an A5 chip for improved performance, and an 8-megapixel camera capable of recording 1080p video. The device runs on the iOS operating system, providing access to a wide range of applications through the App Store. One of the standout features of the iPhone 4S is Siri, a voice-activated personal assistant that allows users to perform tasks using voice commands. The phone also supports iCloud, enabling users to store and sync data across multiple devices. Its design includes a glass front and back, making it sleek and modern.