Today marks the 15th anniversary of the iPhone 4S launch, introducing Siri as a built-in feature of the iPhone for the first time. The iPhone 4S went on sale on October 14, 2011, ten days after its announcement. It initially launched in the United States, Australia, Canada, France, Germany, Japan, and the United Kingdom, retaining the iPhone 4's glass and stainless steel design while introducing substantial internal improvements. The device's defining addition was Siri , which allowed users to make calls, send messages, create reminders, schedule appointments, and ask questions using natural language. Apple highlighted the assistant's ability to interpret requests in context, such as understanding that a question about needing an umbrella was a request for the weather forecast. ‌Siri‌ initially launched in beta, supporting English localized for the United States, United Kingdom, and Australia, alongside French and German. The assistant was exclusive to the iPhone 4S, so owners of older iPhones could not access it simply by installing iOS 5. ‌Siri‌ had already existed as a standalone iPhone app, which launched in February 2010. Apple acquired the company in April that year before integrating its technology into iOS directly. Following the iPhone 4S announcement, Apple removed the original app from the App Store and notified existing users that its service would stop working on October 15. Beyond ‌Siri‌, the iPhone 4S introduced Apple's dual-core A5 chip, which it said delivered up to twice the CPU performance and seven times the graphics performance of the iPhone 4. 4 aperture and support for 1080p video recording.