References to “Speed”
Apple used the letter “S” for models that followed newly designed iPhones, largely retained their appearance, and featured upgraded hardware. The tradition dates back to the iPhone 3GS, released in 2009, where “S” stood for “Speed.” In later periods, the letter came to denote a more powerful version of the same design.
Current status
Thus, a new design was introduced one year, followed by an upgraded version of it the next. “S” models pointed to internal hardware innovations such as a new processor and a better camera.
As smartphones evolved, the distinction between a new design and a minor update became blurred.
Pro timeline
Even when the design remained similar, the processor, camera, display, or other hardware could be extensively upgraded. Apple also expanded its product family with larger-screen, more affordable, and Pro models.
The iPhone XS and XS Max, introduced after the iPhone X in 2018, became the last examples of the “S” tradition. There is no clear statement confirming that Apple has abandoned the letter.
Pro Max timeline
However, direct numbering that began with the iPhone 11 in 2019 continued with the iPhone 12, 13, 14, and 15. Since the Pro and Pro Max suffixes were sufficient to explain the differences between the models, the need for the letter “S” diminished. Although Apple could return to the letter, its large product family and numbering system make that unlikely.