Image sprites are basically a collection of images put into a single image. A web page can contain multiple images and loading them all one by one can be a slow process. By using image sprites only a single image is used and by specifying the area of the image to be displayed the same image can be used multiple times.
For ex : We have a an image.gif which contains the home, forward and back navigation buttons. With the help of css the user can simply specify only the part of the image that is needed. Now the user wants to only display the home part of the image for the home button.
