When and how would you use the vouvoiement in French?

The vouvoiement in French is a form of politness. You would use the "tu" when you are talking to a friend or someone close to you, however you would use the "vous" when referring to a person that you don't know or with a person of authority such as a teacher or an adult.

When using the "tu" and the "vous", you must conjugate the verb to the right person, which would be the second person singular for the "tu" and the second person plural for the "vous".