Tu vs. Ud., By Willie Willson and Matthew Hamilton

  Tu vs. Ud. is a simple concept.  Tu is something you say to someone that you are of equal age to or you are older then them. It is used the informal form of a word.  Ud. (Usted) is something that you would say to someone you respect.  It is the formal version.  For spanish words their are a lot of different situations that require these different forms. For example:  Asking how an old man is doing,"¿Como esta ud?", and asking how a child is doing,"¿Como estas tu?"

Real life application:

An old man walks up to you and asks you "¿como estás tu?" and you answer "muy bien y usted." He says "muy bien gracias."