English uses you for one person and for a whole room. Finnish keeps them apart — rather like you and you all:

	sinä	te
Who	one person — friends, colleagues, shop staff, almost anyone	two or more people — or, very politely, one person
“Are you…?”	Oletko…?	Oletteko…?
“And you?”	Entä sinulle?	Entä teille?

Good news for an English speaker: in today's Finland sinä is normal with almost everyone, strangers included. Using te for one person (teitittely) is reserved for very formal service and for elderly people you don't know.