ART is a proprietary image file format used mostly by the America Online (AOL) service and client software.
Technical details
The ART format (file extension ".art") holds a single still image that has been highly compressed. The format was designed to facilitate the quick downloading of images, among other things. Originally, the compression was developed by the Johnson-Grace Company, which was then acquired by AOL. When an image is converted to the ART format, the image is analyzed and the software decides what compression technique would be best. This conversion was done in the AOL proxy servers and could be optionally disabled by the user. This image conversion process effectively reduced the download time for image files. This technology was once branded as Turboweb and is now known as AOL TopSpeed. (With later versions of the Graphic Workshop Professional software, an ART plugin from Alchemy Mindworks is required for this support.) As of June 2006 the Internet Explorer browser no longer supported ART files when Microsoft released a security update. Among other things, this update removed support for ART files from the Internet Explorer browser in order to help prevent issues where invalid ART data could cause the Internet Explorer software to unexpectedly quit.