Animated GIFs, in contrast, can only support 256 colors per frame -- though there are workarounds for this limitation, the resulting file size is not ideal.
The Animated Portable Network Graphics (APNG) file format is a non-standard extension to the Portable Network Graphics (PNG) specification. It allows for animated PNG files that work similarly to animated GIF files, while supporting 24-bit images and 8-bit transparency not available for GIFs.
As it stands today, animated PNGs, with respect to web browsers, still aren't widely supported. Currently, they only work on Firefox and mobile Safari on iOS 8. The format, however, will be supported by Safari 8 once OS X Yosemite ships. If your browser supports animated PNGs, you should see a bouncing ball below.
Browsers that don't support animated PNGs will nonetheless show the first frame of the file.