Does anyone know what the difference is between Ihr and Du? I know they have different verb conjugations, but according to the website they both mean you. Are they interchangeable?
^ Exactly. One can compare "du" in German to "you" in English and "ihr" in German to "all of you" in English. In spanish, it's like "tu" and "vosotros," if you have a reference point for that.
Consider "You are". "Du bist" is used when you are speaking to a single child, family member, or close friend. Ïhr seid" is used when you are speaking to more than one of the above. "Sie sind" is used when you are speaking to one or more people you don't know all that well or to whom you want to show respect.
German, like most European languages, has two different ways of saying "you." In general terms, one form is for people you don't know very well, and another form is for people you do know quite well. The formal form for "you" in German is "Sie." the more intimate form is "du." Thnk of it this way, you would use "Sie" for a person you would call Mr. or Mrs." You would use "du" for someone you would call by his or her first name.