The enhanced GIF89a specification was released in 1989. It followed GIF87a, the original version introduced by CompuServe in 1987, and added features that made GIF more useful for interactive and animated graphics.
The “89a” label identifies the enhanced version and its release year, rather than a software edition or a compression revision. GIF89a retained GIF's basic structure and LZW image compression while adding extension blocks that could carry display and application-control information.
One historical wrinkle is that surviving technical documentation is dated 31 July 1990, which can make references list 1990 for the document publication. The format version itself is conventionally identified as GIF89a and is described as the 1989 enhancement. For a quiz asking when the enhanced version was released, 1989 is the standard answer.
GIF89a became especially important because its additions supported timed frame display and transparency. Later browser features, including Netscape's looping extension, helped turn multi-image GIF files into the endlessly looping animations familiar today.