You've seen them in message forums, blog posts and countless other corners of the Internet: little looping video clips that typically last no more than a few seconds. Like this one (which you may not be able to see if you're using a mobile device):
If a picture is worth a thousand words, something like this is probably in the mid-five-digits. It's informally referred to as a "reaction GIF," and it's a fun, often funny, often very funny, way to express yourself online -- usually as a reaction (natch) to something else you've seen online.
That green fella up above, for example? You might use that in response to a blog post that made you particularly angry. Or this one if you find something particularly absurd:
Okay, but where do you find these little animations, and how do you deploy them as you travel the Interwebs?
The where is easy: Start at ReactionGIFs.com, which features a large, growing and, most important, categorized collection of snippets. Here you can search for particular people or feelings, or view categories based on a feeling or answer (such as "hell yes!"). There's also a Reddit thread devoted to reaction GIFs. (FYI, some of these images are decidedly NSFW.)
Once you've found a GIF you want to use, the next step is to copy its URL -- that is, the address where it's hosted online. In the case of the above Simpsons GIF, for example, which I found on Reddit, I pulled the address right out of my browser's address bar:
In the case of ReactionGIFs.com, it works much the same: Click the GIF you want, then copy the URL from the address bar. In most browsers you can also right-click a GIF and choose Copy Image URL -- a helpful option in case you're pulling the GIF from a location that doesn't hyperlink the source.
Once you've copied the address, all that remains is to paste it into the right place. If you're a blogger and want to make it part of a post, that usually means choosing the embed-image option, then inserting the URL (as opposed to uploading an image).
Likewise, if you subscribe to a message forum, you may be able to use a reaction GIF as your profile photo -- again just pasting the URL instead of uploading a photo. Many message-board systems allow for this option. Similarly, you can often embed an image (in the form of a URL) when you're posting to message board. But you don't just paste the URL into the text; again, you have to look for an embed-image tool.
What's that? You don't like reaction GIFs? All I can say to that is: