German grammar
Du vs Sie
German keeps informal du and formal Sie separate. The verb form changes with the choice.
Examples
Kommst du heute?
Are you coming today?
du is informal.
Kommen Sie morgen?
Are you coming tomorrow?
Sie is formal.
Wie heißen Sie?
What is your name?
Formal questions often use Sie.
Common mistake
Using du in a formal appointment can sound too casual.