Use an interrogative noun or expression when the answer cannot be only yes or no.
● مَنْ — who?
● أَيْنَ — where?
● مَتَى — when?
● لِمَ — why?
لِمَ ضَرَبْتَ زَيْدًا؟ — Why did you hit Zayd?
The requested information determines which question word you need.