Breakdown of Bist du müde? — Es geht.
sein
to be
du
you (informal singular)
müde
tired
Es geht
I'm OK, so-so
Questions & Answers about Bist du müde? — Es geht.
Why does es geht mean "so-so"?
Gehen usually means "to go" or "to walk". However, the phrase es geht is a very common idiom in German. Literally it means "it goes," but it is used to say "I'm okay," "so-so," or "it's alright." You will also hear it as a standard reply to "How are you?" (Wie geht es dir? or Wie geht's?).
Why is bist at the very beginning of the sentence?
In German, to make a simple yes/no question, you swap the position of the verb and the subject. So, the statement du bist müde (you are tired) becomes the question Bist du müde? (are you tired?). There is no "do" or "does" helper word like in English.
Does the word müde change if I am talking to a man versus a woman?
No! Unlike in some other languages, German adjectives do not change their endings when they come after a verb like "to be". Since müde (tired) comes after bist (are), it stays exactly the same no matter who you are talking to.
How would I ask this same question to a stranger or a boss?
You would need to use the formal "you" (Sie) instead of the informal du. You also have to change the verb to match, so the question becomes: Sind Sie müde?