This techniques is know as css-spirits
. Where all images are combined into one image and call the same image all over the website if necessary. First you should know the advantage of using css-spirits.
1. Each images used in webpage is considered as a one http request
2. Webpage load time depends on number of requests
in a page.
3. As the number of requests is less obviously page load time is less.
4. Also if you use multiple images they consume more space
, so better to combine them into one
Using css property called background
we can call images.
Note: You should know positions of each images while using.
See below links more details..
Hope this will helps you lot..