as an adverb (introducing a direct or indirect question): How do you spell your last name?I don’t know how the system works. (introducing an exclamation): How I hate the winter! (followed by an adjective or adverb): How old is Peter?I didn’t realize how clever she was.It’s surprising how quickly the weather can change. (before ‘much’, ‘many’, ‘few’, or ‘little’): How much do you earn? (introducing a clause that is the subject, object, or complement of another clause): How I spend my free time is a private matter.
as a conjunction (connecting two clauses): You can live your life how you want.