Relative pronouns connect two clauses and add information about a noun. The noun can be a person, a thing, a place, or a time. The relative clause usually comes after the noun it describes. This structure helps make one sentence instead of two.

English uses who, whom, whose, which, and that as main relative pronouns. Who usually refers to people. Which usually refers to things or animals. That is common in defining clauses for people or things, and many speakers prefer it in everyday English.

Use who for a person when the relative pronoun is the subject of the relative clause. Use whom when it is the object, especially in formal English. In modern English, many speakers use who instead of whom, especially in speech. That is also common for people in defining clauses.

Use which for things and animals. Use that in many defining clauses with things. Both which and that are possible in many cases, but that is often more common in speech and simple defining clauses. The choice can be a matter of style, not only grammar.

Use whose to show that something belongs to someone or something. It can describe people, animals, and things. Some speakers feel whose with things is very natural, while others may choose another structure in careful writing. Both patterns exist in real English.

A defining relative clause identifies exactly which person or thing we mean. It gives necessary information, so the sentence meaning changes if we remove it. In these clauses, that is very common, and the choice between who, which, and that can depend on the noun and the style. This module focuses on defining clauses because they are the main pattern for relative pronouns.

In informal English, speakers often omit the relative pronoun when it is the object of the relative clause. This is common with who, whom, which, and that in defining clauses. It is not possible when the relative pronoun is the subject. Omission is a regular feature of natural spoken and written English.

English also uses where and when as relative words with nouns of place and time. Where replaces a pattern with place plus a preposition. When replaces a pattern with time. These words work like relatives because they connect a noun to extra information about it.

You can now choose a relative pronoun to connect a noun with a defining clause. You can use who, whom, whose, which, and that for people, things, and possession. You can also recognize when omission is possible and when where and when work as relative words for place and time. You can understand that some choices, especially whom and that, depend on style and modern usage as well as grammar.