According to Mozilla Labs, Mozilla Gran Paradiso Alpha 7, the beta version of Firefox 3.0, has added Animated PNG display support. Usually we use animated images are GIF, and GIF's 8-bit color depth and 1-bit alpha-channel are its hard wounds. While the PNG format has a 24-bit color depth and an 8-bit alpha-channel, the difference between them I once made this comparison in the icon making article: