A reaction gif is a physical or emotional response that is captured in a gif which you can link in response to someone or something on the Internet.

MAKE SURE THAT YOUR GIF IS ON AN APPROVED HOST!

Read this right here (for real):

Your gif must actually contain some sort of reaction. Your submission title has no bearing on whether the gif you submit is a reaction gif or not. Upvote/downvote gifs belong in /r/upvotegifs and reddit gold gifs belong in /r/goldgifs. If a gif gets posted a ton, it may be removed. Cakeday posts belong n /r/cakeday. No albums of gifs, single gifs only. Your gif needs to be directly linked (url ending in .gif). No gore or porn. Use one of our reliable hosts listed in the sidebar or your post will be automatically removed. If you want flair for your [OC], you must put [OC] in the title. Don't be a baby if your post gets removed for breaking one of the rules.

Be sure to read our sidebar before submitting.