Open question: question word in position 1, verb in position 2. Yes/no question: verb in position 1. There is no "do": Kommst du? = Are you coming? / Do you come? Answer ja, nein, or doch (after a negative question).
wer, wen, wem, wessen who, whom, whosewas whatwann whenwo where (no movement)wohin where towoher where fromwie howwie viel, wie viele how much, how manywie lange how longwie oft how oftenwarum, wieso, weshalb whywelcher, welche, welches whichwas für ein what kind of
- welcher picks from known things and is declined like dieser: Welchen Zug nimmst du?
- was für ein asks what kind of thing. Here für does not decide the case: the role in the sentence does: Mit was für einem Auto fährst du? (dative because of mit).
- Preposition + who / what: mit wem? an wen? for a person, womit? woran? for a thing (see "da- and wo-"). The preposition never goes to the end as in "Who are you waiting for?".
- …, oder? at the end = "isn't it? / right?": Du kommst morgen, oder?
Woher kommst du? Aus Bosnien.
Where are you from? From Bosnia.
Was für ein Buch liest du?
What kind of book are you reading?
Bist du nicht müde? Doch, sehr.
Aren't you tired? Yes, very.