CSS Sprites is a technique of combining multiple images into a single image file for use on a website, to help with performance. Using image sprites will reduce the number of server requests and save bandwidth. Here is the network requests for social icons for my blog. Since I was using 5 icons, browser was sending 5 browsers requests.
To use Sprite first you need to combine the images into one, and then you need to write CSS to show only specific part of the image. Something like this.
And here is the result after using CSS sprites.
The width and height attributes define the size of the image and the background left and top attributes controls the visible portion of the image. Here is a utility which combines the images and generates CSS for the same. You can get it from github