“Who/that” mix-ups are quite common because many people believe that the words may be used interchangeably. In fact, that refers to an object or animal, while who refers to a person.

Incorrect: I hate people that talk on their cell phones while driving.
Correct: I hate people who talk on their cell phones while driving.

Incorrect: If you are a person that can’t sit still for five minutes…
Correct: If you are a person who can’t sit still for five minutes…

Incorrect: He’s a guy that can strike a lot of guys out.
Correct: He’s a guy who can strike a lot of guys out.

Editor’s Note: This is a reader-submitted post.