Interrogative pronouns introduce questions that ask for a person, thing, place, time, reason, manner, or choice. They stand in place of the unknown information and help shape direct questions. In English, several question words are also used in related structures such as Interrogative Adjectives and in the word order of Asking Questions.

Who asks about the subject of a verb and is the usual form in speech. Whom asks about the object of a verb or preposition and is more formal in writing, especially after a preposition. In everyday English, many speakers replace whom with who, but formal writing still preserves the distinction.

Idea	Example
Who asks about the subject of a verb.	Who called you?
Whom asks about the object of a verb or preposition.	Whom did you invite?
Formal English places the preposition before whom.	To whom did you speak?
Informal English often moves the preposition to the end.	Who did you speak to?

Whose asks about possession and replaces an unknown possessor. What asks about things, actions, or information that is not limited to a fixed set. What is broader and more open, while which is used when the speaker chooses from a smaller set of options.

Idea	Example
Whose asks about possession.	Whose book is this?
What asks about things or actions.	What happened?
What is more open in meaning.	What do you need?
Which asks from a limited set of choices.	Which color do you want?

Where asks about place or location, when asks about time, and why asks about reason or purpose. These forms behave like interrogative pronouns in question structure because they stand at the front of the question and identify the missing information. They are central to the patterns used in Asking Questions.

Idea	Example
Where asks about place.	Where is the station?
When asks about time.	When does the meeting start?
Why asks about reason or purpose.	Why are you late?

How asks about manner, means, or degree and often appears with another word to narrow the question. It can ask about the way something is done or about quantity and extent. This form is common in fixed patterns and works closely with sentence patterns taught in Word Order.

Idea	Example
How asks about manner or means.	How did you do it?
How much asks about quantity or degree.	How much does it cost?
How asks about extent.	How tired are you?

In English questions, the wh word normally moves to the front of the clause. Most questions also use auxiliary inversion, so the auxiliary comes before the subject. When the wh word is the subject, inversion is not needed because the question word already fills the subject position.

Idea	Example
The wh word moves to the front of the question.	Where are they going?
Auxiliary inversion follows most wh questions.	What did she say?
No inversion is needed when the wh word is the subject.	Who called you?

Interrogative pronouns identify missing people, objects, places, times, reasons, and methods in questions. Who and whom focus on people, whose marks possession, what and which select or request information, and where, when, why, and how complete the core set of question forms. Their placement and inversion patterns are essential for accurate question formation and support the broader system of English question grammar.