CSS Sprite

Combining several small images into one file and showing parts of it with CSS positioning.

Its value has largely gone with HTTP/2, where parallel requests are cheap; inline SVG is the better answer for icons today.

Existing sprites are worth leaving alone unless they are blocking a redesign.

It solved a real problem under HTTP/1.1, where every request carried a fixed cost.

Recognising it explains a lot of odd markup in older codebases before you optimise around it.