Here's how much the iPhone's software has changed over time

Apple released the first version of iOS, called iPhone OS, in 2007. It shipped on the original iPhone and was based on OS X, the operating system that runs on the Mac.

Apps like Safari, Mail, and Messages were reminiscent of the Mac counterparts, giving the phone a PC-like feel.

Over time, Apple has dramatically changed the way iOS looks, having introduced a slew of new apps and an entire redesign, which launched on the iPhone 5s in 2013.

Here's what iOS looks like over time: