What is CSS Sprite?
The idea was that the computer could fetch a graphic into memory, and then only display parts of that image at a time, which was faster than having to continually fetch new images.
or
Get the image once, shift it around and only display parts of it, saves the overhead of having to fetch multiple images.
In older days, web designers were “slicing” images to make pages load faster. But it fake viewers eyes that the page was loading faster by loading bits and pieces all over at once.
Each one of those images is a separate HTTP-Request, and the more of those, the less efficient your page is.
Tool available to automate. SpriteMe
Cons: They don’t do repeating graphics or it is difficult to achieve.
Rajakvk's Blog 