Computers can be frustrating. There, I said it. (I hope I didn't shock anyone.)
One big frustration is that things you think would be fast are really slow. For example, you're in the middle of typing up a letter and you decide to be a good computer user and save it.
So, you move your hand off the keyboard and over to the mouse, move the mouse up to the program's toolbar, hunt around for the Save icon, click it and then move your hand back to the keyboard. Often during those long seconds, your train of thought is totally derailed.
Fortunately, this is one frustration you don't have to live with. With just a few split-second key presses, you can perform many common computer tasks that would require several mouse movements and clicks. Talk about a time-saver!