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 is similar to its predecessor, the iPhone 4, but includes enhancements in speed and camera quality.