The Giphy tool provides search for the largest collection of GIFs in the world from Giphy. There are actually two different groups, GIFs and stickers.
It's a really straightforward tool.
If you wanted to tell someone that you were upset with them, you could search on "angry" and browse basically forever, because there are tens of millions of images in GIPHYs collection and it changes every day.
Once you see something that captures what you want to communicate visually you put it in your email and you're off to the races and set that's it hope you find it useful.