The iPhone 4S (retroactively stylized with a lowercase 's' as iPhone 4s as of September 2013) is a smartphone that was designed and marketed by Apple Inc. It is the fifth generation of the iPhone, succeeding the iPhone 4 and preceding the iPhone 5. Announced on October 4, 2011 at Apple 's Cupertino campus, its media coverage was accompanied by news of the death of former Apple CEO and co-founder Steve Jobs on the following day.
Orders could be placed on October 7, 2011 and mainstream availability in retail stores began on October 14, 2011 in the United States, Australia, Canada, the United Kingdom, France, Germany, and Japan. Sales peaked over its predecessor with more than a million sales in the first twenty- four hours of order availability and more than four million sales in the first four days of retail availability. Further worldwide rollout, including 22 additional countries on October 28, came over the next several months.
This iPhone was named "4S" where "S" stood for Siri an iPhone 4S-exclusive intelligent personal assistant that was later included in future generations of mobile Apple products. Retaining most of the external design of the iPhone 4, the 4S hosted major internal upgrades, including an upgrade to the Apple A5 chipset, and an 8-megapixel camera with 1080p video recording. It debuted with iOS 5, the fifth major version of iOS, Apple 's mobile operating system, that introduced features including iCloud, iMessage, Notification Center, Reminders, and Twitter integration.
Reception to the iPhone 4S was generally favorable.
