It has dual cameras -- a 5 megapixel HD video/still camera (720p at 30 FPS) with a "backside illuminated sensor," a 5X digital zoom, and an LED flash on the rear and a VGA quality video/still camera on the front designed for video conferencing over a Wi-Fi network with Apple's included "FaceTime" application. It has dual noise-cancelling microphones also.
It is powered by an "Apple A4" processor of unspecified speed, has 512 MB of RAM, and has 8 GB, 16 GB, or 32 GB of internal storage (8 GB configuration introduced October 4, 2011). Network support includes UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz) and GSM/EDGE (850, 900, 1800, 1900 MHz). 802.11g/n and Bluetooth 2.1+EDR are supported as well.
Like the iPhone 3GS that came before it, the iPhone 4 includes a digital compass, A-GPS, and an accelerometer, but adds a 3-axis gyroscope to its list of sensors for additional 3D gaming options.
Apple reports that the iPhone 4 provides "up to" 40 hours of audio playback, 14 hours of talk time on 2G, 7 hours of talk time on 3G, 6 hours of Internet use on 3G, 10 hours of Internet use on Wi-Fi, 10 hours of video playback and 300 hours of standby time.
In the US, for new/qualified AT&T Wireless customers, the 16 GB configuration originally was US$199 and the 32 GB configuration originally was US$299 with a two year contract. Starting June 14, 2011, in the US, Apple also began offering this iPhone 4 unlocked in white or black for US$649 with 16 GB of storage and US$749 with 32 GB of storage (and discontinued these options on October 4, 2011).
On October 4, 2011, Apple introduced a lower-end 8 GB configuration for US$99 subsidized by a two-year AT&T contract and also made this configuration available unlocked in the US for US$549 (and discontinued this option on September 12, 2012).
Finally, on September 12, 2012, Apple dropped the price of the 8 GB iPhone 4 (GSM) model to US$0 with a two-year contract or US$450 unlocked and contract-free. It was discontinued on September 10, 2013, with the exception of mainland China, where it remained available for RMB 2,588 until September 9, 2014.
Like the iPhone 4, the iPhone 4S uses the same all stainless steel body design with an ultra high-density 3.5-inch, IPS, LED-backlit 960x640 326 ppi multi-touch "retina" display, dual noise-cancelling microphones, mobile and data antennas integrated in the "metal band" that wraps around the sides of the phone, and a chemically hardened "aluminosilcate" glass front over both the display and a black or white frame and the chemically hardened black glass back, too. Both the front and back have an "oleophobic" oil repellent coating, as well.
However, the iPhone 4S is a "world phone," supporting both GSM and CDMA networks (UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz); GSM/EDGE (850, 900, 1800, 1900 MHz), and CDMA EV-DO Rev. A (800, 1900 MHz), and the "antenna automatically switches between send and receive." It supports 802.11b/g/n, Bluetooth 4.0, and HSDPA of up to 14.4 Mbps, too.
The iPhone 4S also has dual cameras -- an 8 megapixel HD video/still camera (1080p at 30 FPS) with a "backside illuminated sensor," and an LED flash on the rear and a VGA quality video/still camera on the front designed for video conferencing over a Wi-Fi network with Apple's included "FaceTime" application.
It is powered by a dual-core "Apple A5" processor, has 512 MB of RAM, and has 8 GB, 16 GB, 32 GB, or 64 GB of internal storage (the 32 GB and 64 GB options were discontinued September 12, 2012, the 16 GB option was replaced by an 8 GB option on September 10, 2013, and this 8 GB configuration was discontinued on September 9, 2014).
Apple reports that the iPhone 4S provides "up to" 40 hours of audio playback, 14 hours of talk time on 2G, 8 hours of talk time on 3G, 6 hours of Internet use on 3G, 9 hours of Internet use on Wi-Fi, 10 hours of video playback and 200 hours of standby time.
In the US, the iPhone 4S originally was available locked to and subsidized by either AT&T, Sprint or Verizon with 16 GB, 32 GB or 64 GB of storage, for US$199, US$299, or US$399, respectively, with a two-year contract. It also originally was available "unlocked and contract-free" for US$649, US$749, and US$849.
On September 12, 2012, Apple dropped the price of the 16 GB carrier-locked model to US$99 with a two-year contract and dropped the unlocked and contract-free option to US$549.
Finally, on September 10, 2013, Apple introduced a lower capacity 8 GB model that was US$0 in the US locked to AT&T, Sprint, or Verizon with a two-year contract. This model was US$450 if unlocked and contract free. It was discontinued entirely on September 9, 2014.
Unfortunately, the unlocked model is manually blocked from working on CDMA networks.
*For those interested in the smallest of details, Apple quietly changed the name of the iPhone 4S to iPhone 4s (lower case) on September 10, 2013, presumably for consistency with the iPhone 5s models introduced at the same time.