Copied from source (read source for more infomation):
"The Animated Portable Network Graphics (APNG) file format is an 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."
Here is a demo displaying the advantages of a APNG file over GIF format. The file sizes are very similar and I wish it was more globally supported.
I would like to see this implemented natively in the alertbox and SLOBS. It's been many times where I would try to use an animated GIF where it just wouldn't work properly due to nature of the format. It would always show extra pixels or some kind of defect, after creation.
*Microsoft Edge/Explorer doesn't support APNG.