The iPhone 4S (retroactively stylized with a lowercase ‘s’ as iPhone 4s as of September 2013) is a touchscreen-based smartphone developed, manufactured, and released 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 the death of former Apple CEO and co-founder Steve Jobs on the following day. Available for pre-order on October 7 and coming to mainstream availability in retail stores on October 14 in the United States, Australia, Canada, the United Kingdom, France, Germany, and Japan, sales peaked over its predecessor with over a million sales in the first twenty-four hours of preorder availability and over 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 (Apple CEO Tim Cook confirmed that during the Q&A session at the D10 conference in May 2012), an iPhone 4S-exclusive intelligent personal assistant that was later included in future generations of mobile Apple products. Retaining the external design of the iPhone 4, the 4S hosted revised hardware specifications, most notably 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 was generally favorable. Reviewers noted Siri, the new camera, and processing speeds as significant advantages over the prior model. It was succeeded by the iPhone 5 as Apple’s flagship phone on September 12, 2012. The iPhone 4S remained in production, albeit being sold for free and with reduced storage (16/32/64 GB to 8 GB.) It was officially discontinued on September 9, 2014 following the announcement of the iPhone 6.