Developer reviews have detailed every spec of the iPhone 4S, which released on Oct. 14 and has sold over 4 million handsets during its debut weekend, but many are still wondering about what the "S" in iPhone 4S stands for.
There have been inconsistencies in the names of iPhones ever since its second-generation was released in 2008.
Commentators have noted that Apple bypassed the name "iPhone 2" and called the device the iPhone 3G, after the network on which is runs.
The third-generation smartphone was called the iPhone 3GS.
Many say the "S" in this name stands for "speed" as Apple advertised the iPhone 3GS as having a new processor that made it up to twice as fast as its predecessor.
The iPhone 4 was accordingly named after its fourth-generation place in the Apple smartphone line.
For months preceding its release, rumors indicated that the fifth-generation iPhone would be called the iPhone 5, and that the iPhone 4S would be a low-cost model to cater to customers who couldn't afford higher end models.
Some rumors indicated that the iPhone 5 was to have the same outer look as the iPhone 4, but would have a faster processor and a better camera.
That rumor turned out to be true for the iPhone 4S.
Commentators have suggested a number of possible meanings for the "S" in iPhone 4S.
Some believe that the "S" stands for "shutter," referring to the highly efficient, 8MP camera featured on the iPhone 4S.
Some believe that the "S" stands for "Siri," referring to the smartphone's primary feature, the virtual personal assistant, Siri.
Some believe that the "S" stands for "Steve," indicating that the iPhone 4S was dedicated to the late Steve Jobs, co-founder and former CEO of Apple, and suggesting that the name can be read as "iPhone 4 Steve."
Jobs passed away on Oct. 5, just one day after the iPhone 4S was unveiled.
As the iPhone 4S stands as the fifth-generation of the iPhone line, many feel the most appropriate name for the next iPhone would be the iPhone 6, in order to match up with its order in the iPhone family.