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Filename extension
Internet media typeapplication/x-navi-animation
Magic numberACON (4 bytes, ASCII)
Developed byMicrosoft
Type of formatanimated raster image format for mouse cursors

The ANI file format is a graphics file format used for animated mouse cursors on the Microsoft Windows operating system.

The format is based on the Microsoft Resource Interchange File Format, which is used as a container for storing the individual frames (which are standard Windows icons) of the animation.

File structure

Animated cursors contain the following information: (in order of position in the file)

Frame rates are measured in jiffies, with one jiffy equal to 1/60 of a second, or 16.666 ms.


Sequence information present in the file determines the sequence of frames, and allows frames to be played more than once, or in a different order than that in which they appear in the file. For example, if the animation contains three different images numbered 1, 2 and 3, and the sequence is 1-2-3-2-1, (five frames) then only three icons need to be stored in the file, thereby saving storage space.

See also