A hook can be anything that will make the reader want to read more. It can be a surprising fact, a personal anecdote, or a thought-provoking question. The most important thing is that it makes the reader curious about what comes next.
Here are a few examples of hooks that you could use in an essay:
* "In the United States, there are more than 2 million people who live with multiple sclerosis."
* "When I was 16 years old, I was diagnosed with cancer."
* "Why do we dream?"
These are just a few examples, and there are many other ways to grab the reader's attention. The best hook is one that is relevant to your essay topic and that will make the reader want to learn more.