I didn't even know what these things are until today. Apparently, if you combine all your website images into one large image, and then just display the relevant portion of that image, you speed up your website. I've been playing with this today and it does seem to work, although it is not a dramatic effect.
I found an excellent tutorial on this at:
http://css-tricks.com/css-sprites/
And a handy tool for creating css sprites at:
SpriteMe
I found an excellent tutorial on this at:
http://css-tricks.com/css-sprites/
And a handy tool for creating css sprites at:
SpriteMe