It plays itself, everywhere. A GIF starts on its
own in a chat, a pull request or a document, with no player and no
tap. That's the whole reason the format outlived its own obsolescence.
Showing a bug or a feature. A three-second GIF in a
GitHub issue explains what a paragraph can't, and it loops until the
reader has seen it.
A reaction or a joke. Short, small and silent is
the point: nobody watches a reaction with the sound on.
Somewhere video isn't allowed. Email signatures,
some documentation and older forums take an image but not a video.
Keep it small. Chat apps cap what they'll take
(see the platform limits); if it's
still too big, take a shorter stretch or a smaller width. For sharing the video itself
instead, compress video gets it under
a size without turning it into pictures.