Sorry, it's long but at least it's an answer :)
In Spanish, there are different ways of saying 'you,' depending on whom you are speaking to. When speaking to a friend, a child, or a family member, for example, you would use the word tĂș. This is informal, and so it would be used if you were addressing someone you are familiar with and comfortable with.
However, if you were addressing someone you do not know, like a store clerk, or someone in a position of power, like the president, then you would want to use the word usted. Usted is a more formal way of saying 'you.' When meeting someone new, generally, usted is used.