̶N̶e̶t̶s̶c̶a̶p̶e̶ ̶a̶d̶d̶e̶d̶ ̶a̶n̶i̶m̶a̶t̶i̶o̶n̶ ̶t̶o̶ ̶G̶I̶F̶s̶. Edit: Netscape added looping to animated GIFs per reply. She apparently led that effort. The press is misreporting her actions as having invented GIF in the first place, which is wrong. That happened at CompuServe in 1987.

https://en.wikipedia.org/wiki/GIF#Animated_GIF

GIFs already had animation. Netscape added an animation loop counter.

For a rough idea of the complexity involved, when I wrote a GIF decoder and renderer a few decades ago, implementing the loop counter extension took me about 10 minutes.