In the previous video format conversions the formats supported audio without any additional encoding. A Graphic Interchange Format or GIF is a bitmap image format without an audio component.
GIFs have been around since the late 80s and are still used to this day on web forums, Discord, text messages and everywhere in between. Because GIFs are just animated image frames, they are easy to send all over the internet without needing a video player. As with most conversions, the FFmpeg command is simple:
$ ffmpeg -i input.mp4 output.gif
Tip: Twitter does support the GIF format while Instagram natively does not.