If you need a little Spanish 101 refresher, usted is the formal "you," typically used to show respect. Tu is the informal version. Guatemalans also use vos, which I'll describe as a common slang. Kinda like if we all said "dude" a lot more often. Maybe?
I had some questions about how these pronouns influence DTR conversations. Billy's responses are fantastic (and not at all what I expected)! Check it out.
So, seriously, is this crazy? How do you decide which "you" to use?