What exact date is listed as GIF's initial release?

GIF's initial release is listed as 15 June 1987.

The Graphics Interchange Format was developed at CompuServe by a team led by computer scientist Steve Wilhite. CompuServe introduced it as a color image format for its file-download areas, replacing an earlier black-and-white run-length encoding system.

The first specification was called GIF87a, and it already supported storing multiple images in one stream. That capability later helped make animated GIFs possible, although animation controls were added in the enhanced GIF89a specification.

A frequent confusion is between GIF's initial release date and later milestones. GIF89a was released in 1989, while web browsers did not gain widely used looping animated-GIF support until Netscape Navigator 2.0 added it in 1995. The format's compact files and broad compatibility helped it spread across early online services and the young World Wide Web.