Happy Birthday Photoshop

Believe it or not Adobe Photoshop turned 20 yesterday. I didn't realize it was that old. As a young designer it is hard to imagine life without Photoshop. Beyond MS Paint (which I don't think counts as graphics software), Photoshop was the first and has become the only software I use for on screen design. It was introduced 6 years after the first mouse shipped with a Mac, and way before digital photography became mainstream. I wonder why they called it Photoshop?