Relative Pronouns

Use who to refer to people when the relative clause describes or identifies a person. Who can be the subject or object of the clause.

Use whom to refer to people when the relative clause treats the person as an object, especially in more formal contexts. You can often replace whom with who in speech.

Use whose to show possession or association and it can refer to people, animals, or things. The relative clause tells you who owns or is connected to something.

Use which to refer to things or animals when the relative clause gives extra information or identifies a particular thing. Which is often used in non-defining clauses with commas.

Use that to refer to people, things, or animals in defining relative clauses that are essential to identify the noun. That cannot be used in non-defining clauses.

Use where to refer to places and the relative clause describes a location related to the noun. Where makes sentences shorter and more natural when talking about place.

Use when to refer to times and the relative clause describes a moment or period related to the noun. When is useful for events or dates.

Use why to refer to reasons, typically after nouns like reason, so that the relative clause explains a cause or motive.

Defining relative clauses give essential information to identify the noun and do not use commas; non-defining clauses add extra, non-essential details and are set off by commas. Relative pronouns like that cannot appear in non-defining clauses.

Relative pronouns such as who, whom, whose, which, that, where, when, and why link clauses by referring back to people, things, places, times, or reasons; choosing the right pronoun and paying attention to whether the clause is defining or non-defining ensures clear and precise sentences.