Himself is a pronoun people use when referring back to a male person already mentioned in the sentence. When you say “Marcus taught himself to play the guitar,” the word himself points back to Marcus, showing he was both the teacher and the student.

The word does two main jobs. First, it shows that someone did something to or for the same person: “The chef prepared himself a meal” means the chef cooked for himself, not for someone else. Second, it adds emphasis: “The principal himself came to watch our play” stresses that this wasn't just any staff member, but the principal personally.

You'll sometimes hear people say someone is “not himself today,” meaning he's acting differently than usual, perhaps because he's sick or upset. When someone wants to be alone, they might say they need time “by himself.”

Himself is part of a family of similar words: herself, myself, yourself, themselves, and itself. These are called reflexive pronouns because they reflect back to someone already named, like a mirror reflects your image back to you.