The i- prefix for Apple products was created as part of the iMac
in the late 90s and was adopted into a full product line shortly
after. The original meaning was "internet", meaning the iMac was
capable of internet connectivity out of the box.
Later Apple and Steve
Jobs used it more to refer to individual, innovation, instruct,
inform, and inspire.
It became a handy and easy to remember code for all things
Apple.