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. It was announced on October 4, 2011, at Apple's Cupertino campus, and was the final Apple product announced in the lifetime of former Apple CEO and co-founder Steve Jobs, who died 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 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 on sale, albeit being sold with reduced storage (from 16/32/64 GB down to 8 GB). The 4S was officially discontinued on September 9, 2014 following the announcement of the iPhone 6, although production did continue for developing markets until February 17, 2016. During the course of its lifetime, the iPhone 4S was one of the best-selling iPhones ever produced and it is the first iPhone to support five major versions of iOS: iOS 5, iOS 6, iOS 7, iOS 8, and iOS 9 (the iPad 2 was supported from iOS 4 to iOS 9). The 4S is also the last iPhone to have the original 30 pin connector as the succeeding iPhone 5 replaced it with the all digital Lightning Connector.

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The iPhone 4 is a smartphone that was designed and marketed by Apple Inc. It is the fourth generation of the iPhone lineup, succeeding the iPhone 3GS and preceding the 4S. Following a number of notable leaks, the iPhone 4 was first unveiled on June 7, 2010, at Apple's Worldwide Developers Conference in San Francisco, and was released on June 24, 2010, in the United States, United Kingdom, France, Germany, and Japan. The iPhone 4 introduced a new hardware design to the iPhone family, which Apple's CEO Steve Jobs touted as the thinnest smartphone in the world at the time; it consisted of a stainless steel frame which doubled as an antenna, with internal components situated between two panels of aluminosilicate glass. The iPhone 4 also introduced Apple's new high-resolution "Retina Display" (with a pixel density of 326 pixels per inch), while maintaining the same physical size and aspect ratio as its precursors. The iPhone 4 also introduced Apple's A4 system-on-chip, along with iOS 4—which notably introduced multitasking functionality and Apple's new FaceTime video chat service. The iPhone 4 was also the first iPhone to include a front-facing camera, and the first to be released in a version for CDMA networks, ending AT&T's period as the exclusive carrier of iPhone products in the United States.

The iPhone 4 received largely positive reception, with critics praising its revamped design and more powerful hardware, in comparison to previous models. While it was a market success (with over 600,000 pre-orders within 24 hours), the release of the iPhone 4 was plagued by highly publicized reports concerning abnormalities in its new antenna design that caused the device to lose its cellular signal if held in a certain way. Most human contact with the phone's outer edge would cause a significant decrease in signal strength. Apple released iOS 4.0.1 to unsuccessfully try and fix these issues.

The iPhone 4 spent the longest time as Apple's flagship iPhone model at fifteen months. Although the succeeding 4S was announced in October 2011, the 4 continued to be sold as a midrange model until September 2012, and thereafter as the entry-level offering in Apple's lineup until September 2013 with the announcement of the iPhone 5S/iPhone 5C. The iPhone 4 had the longest lifespan of any iPhone ever produced, spanning close to four years and available in some developing countries until early 2015.

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The iPhone 3GS (originally styled iPhone 3G S) is a smartphone that was designed and marketed by Apple Inc. It is the third generation iPhone and the successor to the iPhone 3G. It was unveiled on June 8, 2009 at the WWDC 2009 which took place at the Moscone Center in San Francisco.

This iPhone is named "3GS" where "S" stood for Speed (Phil Schiller had mentioned it in the launch keynote). Improvements include performance, a 3-megapixel camera with higher resolution and video ability, voice control, and support for 7.2 Mbit/s HSDPA downloading (but remains limited to 384 kbps uploading as Apple had not implemented the HSUPA protocol). It was released in the United States, Canada, and six European countries on June 19, 2009, in Australia and Japan on June 26, and internationally in July and August 2009.

The iPhone 3GS runs Apple's iOS operating system. It was succeeded as Apple's flagship smartphone in 2010 by the iPhone 4. On June 24, 2010 an 8GB model was released, discontinuing the 16 and 32GB models. However, the 3GS continued in production until September 2012 when the iPhone 5 was announced.

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The iPhone 3G is a smartphone designed and marketed by Apple Inc.; it is the second generation of iPhone, successor to the original iPhone, and was introduced on June 9, 2008, at the WWDC 2008 at the Moscone Center in San Francisco, United States.

The iPhone 3G is internally similar to its predecessor, but included several new hardware features, such as GPS, 3G data and tri-band UMTS/HSDPA. The device was originally loaded with the concurrently launched iPhone OS 2.0. In addition to other features (including push email and turn-by-turn navigation), this new operating system introduced the App Store—Apple's new distribution platform for third-party applications.

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Development of the iPhone as a product began in 2005 and continued in complete secrecy until its public unveiling. The device broke with prevailing mobile phone designs by eliminating most physical hardware buttons, and eschewing a stylus for its screen-based interface, instead featuring only a few physical buttons and a touch screen. It featured quad-band GSM cellular connectivity with GPRS and EDGE support for data transfer, and made use of continuous internet access and onboard processing to support features unrelated to voice communication. This approach has been emulated by most new smartphone designs that followed. Its successor, the iPhone 3G, was announced in June 2008.

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