English grammar: Relative clauses defining

What this grammar point covers

A defining relative clause is a part of a sentence that gives essential information about a noun. It tells us exactly which person or thing we mean.

When to use it

Use defining relative clauses in English when you need to give important information that identifies someone or something. Without this information, the meaning of the sentence is not clear.

Key forms

• who (for people)
• which (for things/animals)
• that (for people or things)
• The clause comes directly after the noun it describes.

Examples

Tips

• Do not use a comma before a defining relative clause.
• You can use 'that' instead of 'who' or 'which' in most cases.
• Do not use 'what' to introduce a relative clause.

Exceptions and edge cases

• In spoken English, 'that' is often used instead of 'who' or 'which'.
• Sometimes, the relative pronoun can be left out if it is the object of the clause (e.g., 'The book (that) I read was interesting.').