CSS sprites technique is a way to reduce the number of HTTP requests made for image resources, by combining images in a single file.
An image sprite is a collection of images put into a single image.A web page with many images can take a long time to load and generates multiple server requests.
Using image sprites will reduce the number of server requests and save bandwidth.
Sprites are two-dimensional images which are made up of combining small images into one larger image at defined X and Y coordinates.
To display a single image from the combined image, you could use the CSS background-position property, defining the exact position of the image to be displayed.
Instead of using three separate images, we use this single image ("img_navsprites.gif"):
With CSS, we can show just the part of the image we need.In the following example the CSS specifies which part of the "img_navsprites.gif" image to show:
<img id="home" src="img_trans.gif">- Only defines a small transparent image because the src attribute cannot be empty. The displayed image will be the background image we specify in CSS
width: 46px; height: 44px;- Defines the portion of the image we want to use
background: url(img_navsprites.gif) 0 0;- Defines the background image and its position (left 0px, top 0px)
This is the easiest way to use image sprites, now we want to expand it by using links and hover effects.
We want to use the sprite image ("img_navsprites.gif") to create a navigation list.We will use an HTML list, because it can be a link and also supports a background image:
Now start to position and style for each specific part : -
Our new image ("img_navsprites_hover.gif") contains three navigation images and three images to use for hover effects:
Because this is one single image, and not six separate files, there will be no loading delay when a user hovers over the image.We only add three lines of code to add the hover effect : -