1. Things YOU do. These would all follow "tú" (you) in a sentence.
2. Things I do. These would all follow YO in a sentance.
3. Actions that a group of people are doing. This may start with "mis amigos" or "los estudiantes" or "muchos perros"
4. Things done by a single, random person [he, she, Bill, the cat, Aubrey, Sam, the girl, the child]
