With the release of iOS 8, Safari has gained the ability to display Animated PNGs (APNGs). Originally proposed in 2004 as a replacement to animated GIF images, APNGs offers more color and transparency support over GIFs.
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. It also retains backward compatibility with non-animated PNG files.
The APNG specification, however, was rejected by the PNG group in 2007, so support for the format has been rather limited. In fact, the format has been declared dead due to the lack of official adoption. Firefox was the only major browser that provided standard support for APNG, until iOS 8.
The beach ball image in this article is animated when viewed in iOS 8 or Firefox. Edit: and OS X Yosemite.