Relative Clauses (who, which, that)

Advanced · Clauses

Relative clauses let you add information about a noun inside the same sentence, so you do not need two short sentences. Instead of "I have a friend. She lives in Paris," you say "I have a friend who lives in Paris."

The joining words are relative pronouns: "who" for people, "which" for things, and "that" for both. A key skill is knowing when to use commas (and when not to).

How to build it

noun + who / which / that / whose / where / when + clause

Rules & examples

  1. who = people, which = things, that = both (informal).

    Choose based on what you are describing.

    • The man who called is my boss.
    • The book which/that I read was great.
  2. Defining clauses give essential information — NO commas.

    Remove it and the sentence loses its meaning: which man? which book?

    • The woman who lives next door is a doctor.
  3. Non-defining clauses add extra, non-essential info — use commas, and never "that".

    The sentence still makes sense without this clause.

    • My brother, who lives in Paris, is visiting.
  4. whose = possession; where = place; when = time.

    For belonging, locations, and times.

    • The girl whose bag was stolen cried.
    • The town where I grew up is small.
  5. You can drop the pronoun when it is the object of the clause.

    Common in everyday English.

    • The film (that) I saw was good.

Tips to remember

  • Comma test: if the clause is EXTRA information (you could put it in brackets), use commas and "which/who" — not "that".
  • Use "whose" for possession, for both people and things: "the company whose profits fell".

Common mistakes

  • ✗ The book what I read was good. → ✓ The book that I read was good. — Use "that/which" for things, not "what".