Scroll over a photo, see some text

I had a question tonight about how to make a small message pop up when you scroll over a photo (without using a rollover image). So, I decided to look at how the good folks at xkcd.com do it. (Their comics always contain an extra punchline when you roll your cursor over the art. Today's is pretty awesome.)

The answer is to add a title attribute within the image tag. It goes like this:





Simple, huh?