Answer: GIF

Despite being over a quarter century old, animated GIFs show no sign of fading away anytime soon. From image board posts to forwarded emails, animated GIF files remain the most frequently used animated image files around.

The Graphics Interchange Format (GIF) was introduced to the world by CompuServe in 1987 to serve as a standardized color-enabled graphics format intended to replace their previous black-and-white only format RLE. GIF rapidly became the image format of choice for users in and outside of the CompuServe system thanks to excellent compression which made downloading larger images over slower dial-up modems bearable.

In 1989, CompuServe rolled out several upgrades to the GIF format including the introduction of an animation delay timer–the original release of GIF supported multiple image streams within the container but had no mechanism for displaying them sequentially. The introduction of the animation delay marked the start of the GIF format’s rise to ubiquity. Over the next decade, thanks to the explosion of the Web and the widespread support for GIF in Web browsers, animated GIF files would appear everywhere from the Under-Construction pages of mid-1990s web sites to the image forums of popular discussion boards.

Despite the introduction of newer and technologically superior formats–such as MNG/APNG, animated variants of the PNG format–GIF remains the most widely used and recognized animated image format on the internet.

Bonus Trivia: Although GIF would appear as if it should be pronounced with a hard G like “gun”, borrowing the G sound from its full name Graphics Interchange Format, it is actually pronounced with a soft G like “George” and sounds the same as “JIF” the American peanut butter brand. The original format designers would often joke, echoing the JIF peanut butter slogan, “Choosy developers choose GIF”.