Tu vs Vous

Vous is the formal ‘you’ form.Using it shows respect and social distance. It should always be used when addressing strangers except for in certain environments like school where students normally use tu with each other.Permission should be asked before using tu, but you normally shouldn’t ask if someone is significantly older than you.It should always be employed when addressing people of authority like your teachers. Monsieur Sarkozy or the police.

Vous êtes le nouveau locataire, non?

You are the new tenant, no?

Vous is also used for plural you.  Vous êtes fous. You (all) are crazy. Vous voulez un gateau, les enfants. You want a cake, children.