What is the alt button on a keyboard for? There is no good reason why it is on the keyboard in front of you right now, but at one point it served a very vital function. The alt key is short for alternate reality key. Back when I first invented the modern desktop (yup, that was me), I included the alternate reality key mainly because I knew that email would later be invented and that people would often wish that they had the ability to create an alternate reality after they thought about what it was they had just read.
Um, as brilliant as I am, that was not one of my best ideas. There were lots of bad implications, so I used the alt key to create an alternate reality in which the alt key was completely benign. I was so concerned about removing its current function I didn't bother to create a new function for it. However, thankfully I did have the foresight in my alternate reality to have someone else invent the desktop so that people wouldn't get suspicious of the alt key.