* Pronoun: This is the most common use of "who." It acts as a subject or object pronoun, replacing a noun that refers to a person.
* Subject: *Who* are you?
* Object: I know *who* did it.
* Interrogative pronoun: When "who" starts a question, it's an interrogative pronoun.
* *Who* is coming to the party?
* Relative pronoun: "Who" can also introduce a relative clause, providing more information about a noun.
* The man *who* lives next door is a doctor.
It's important to look at the sentence structure to determine the specific part of speech "who" is acting as.