क्यों

क्यों means why. Put it before the verb, or before the word you are asking about. The rest of the sentence keeps its normal order.

With a two-part verb, क्यों can also sit in the middle. Both of these are natural: आप क्यों हँस रहे हैं? and आप हँस क्यों रहे हैं? (Why are you laughing?)

With a description, क्यों usually comes right before है: दरवाज़ा बंद क्यों है? (Why is the door closed?)

Add नहीं for why not: तुम आज स्कूल क्यों नहीं जा रहे? (Why aren't you going to school today?). As in other negative sentences, the final हो is often dropped.

Answer with क्योंकि (because): क्योंकि मैं बीमार हूँ (Because I'm ill). In conversation, a short reason on its own is fine, and क्यों? alone means Why?