A hoax is like a trick or a made-up story. It's something that is meant to make you believe something that isn't true. For example, someone might create a fake website or story to make people think something happened that didn't really happen, or to make people think something is true that isn't. Hoaxes can be dangerous, because they can cause people to do things that aren't true or are harmful. It's important to be careful and make sure you check that information you receive is true before you believe it or act on it.