Does only GIF support animation?

Taken from the Meta Topic on Post Formatting, an animated SVG file:

^{Image author: Pumbaa80 via Wikimedia}

NOTE: This is not widely as accepted as GIF, so things like some versions of Internet Explorer will show the image by default but it will not be animated.

There is a format of PNG out, APNG, that does what GIF does but better. It is still not supported in all browsers, but it is on the rise.

Edit:

Since the libpng(used by blink in chrome/opera/chromium) committee has locked up, and as it does not seem like any changes will come soon, a better choice might be to use Video with alpha-channel.

Shown here: Video transparency Example

Google says (http://en.wikipedia.org/wiki/Graphics_Interchange_Format#Animation_formats):

Animated GIF remains widely used, as many applications are capable of creating the files, and it remains the only animation format supported in nearly all modern web browsers without the use of a plug-in.

There are other animation formats like for example MNG (http://en.wikipedia.org/wiki/Multiple-image_Network_Graphics). Embedded Adobe Flash objects, MPEG, WebM, and other video formats can be used in place of animated GIF in many websites.

The new image format from Google, WebP, supports animated images, lossless and lossy [1], but even Chrome still doesn't support it yet [2].