With the growing popularity of mobile browsing, designers are making heavy use of sprites in conjunction with the CSS background-position property. Instead of creating a number of individual images that each requires a separate http-request for the browser to fetch it, you can create one file - a Sprite - that includes all the smaller images packaged into one document. You then show and hide the appropriate image in the Sprite by setting its X and Y coordinates within the parent container. Fireworks CS6 does all the math and writes all the CSS for you when you use its new Export as CSS Sprites feature.