APNG

Animated PNG

An animated PNG, or APNG, of a bouncing ball (displays as static image in some web browsers)
Filename extension	.png, .apng
Internet media type	image/png, image/apng, image/vnd.mozilla.apng
Developed by	Mozilla Foundation (adopted by W3C)
Initial release	August 27, 2004; 19 years ago (2004-08-27)[1]
Type of format	animated lossless bitmap image
Extended from	PNG
Open format?	yes

Animated Portable Network Graphics (APNG) is a file format which extends the Portable Network Graphics (PNG) specification to permit animated images that work similarly to animated GIF files, while supporting 24 or 48-bit images and full alpha transparency not available for GIFs. It also retains backward compatibility with non-animated PNG files.

The first frame of an APNG file is stored as a normal PNG stream, so most standard PNG decoders are able to display the first frame of an APNG file. The frame speed data and extra animation frames are stored in extra chunks (as provided for by the original PNG specification). APNG competed with Multiple-image Network Graphics (MNG), a comprehensive format for bitmapped animations which was created by the same team as PNG and is obsolete. APNG's advantage was the smaller library size and compatibility with older PNG implementations.