Relative Clauses

What Are Relative Clauses?

Relative clauses are an essential part of English grammar that allow us to add extra information about a noun without starting a new sentence. They act like adjectives — they describe, identify, or give more detail about a person, thing, place, or time that has already been mentioned. By using relative clauses, we can combine short, choppy sentences into longer, more sophisticated ones. Instead of saying "I have a friend. She speaks four languages," we can say "I have a friend who speaks four languages." The underlined part is a relative clause.

Relative clauses always begin with a relative pronoun (or sometimes a relative adverb). The most common ones are who, which, that, whose, where, and when. These small words connect the main clause to the relative clause and tell us which noun we are talking about. Without relative clauses, our English would sound repetitive and childish. With them, we can express complex ideas in a single, elegant sentence.

There are two main types of relative clauses: defining (also called restrictive) and non-defining (also called non-restrictive). A defining clause tells us which person or thing we mean — without it, the sentence loses its meaning. A non-defining clause gives extra information that can be removed without changing the core meaning of the sentence. Understanding the difference between these two types is one of the most important grammar skills at the B1–B2 level.

Relative Pronouns

Relative pronouns are the connecting words that introduce a relative clause. Each pronoun has a specific role: some refer to people, some to things, and some to possession, place, or time. Choosing the correct relative pronoun depends on what kind of noun it refers to and whether it functions as the subject or object of the clause.

Defining Relative Clauses

A defining relative clause (also called a restrictive relative clause) gives us essential information about the noun it describes. Without this clause, we would not know which person or thing the speaker is talking about. Defining clauses are written without commas because they are a necessary part of the sentence.

Non-Defining Relative Clauses

A non-defining relative clause (also called a non-restrictive relative clause) provides extra, additional information about a noun that is already clearly identified. This information is like a bonus — if you remove it, the sentence still makes complete sense. Non-defining clauses are always written with commas to separate them from the main clause.

Subject vs. Object Relative Clauses

Relative clauses can be divided into two categories based on the role of the relative pronoun within the clause: subject relative clauses and object relative clauses. In a subject relative clause, the pronoun is the subject of the verb in the clause. In an object relative clause, the pronoun is the object — and there is already a separate subject performing the action.

This distinction is crucial because it determines whether the relative pronoun can be omitted. In object relative clauses, the pronoun can be dropped; in subject relative clauses, it cannot.

Omitting the Relative Pronoun

One of the trickiest aspects of relative clauses is knowing when you can leave out (omit) the relative pronoun. In many everyday sentences, native speakers drop the pronoun entirely, and the sentence still sounds perfectly natural. However, there are strict rules about when this is — and is not — allowed.

Example Sentences

Relative Clauses with Prepositions

When a relative clause contains a preposition, the preposition can appear in two positions: at the end of the clause (informal) or at the beginning, directly before the relative pronoun (formal). The formal version sounds more academic and is preferred in written English, while the informal version is more common in everyday speech.

Common Mistakes

Even advanced learners make errors with relative clauses. Here are the most common mistakes and how to avoid them. Study each one carefully — recognizing these errors will immediately improve both your writing and your exam scores.

Defining vs. Non-Defining — Complete Comparison

Now that we have explored both types in detail, let us put them side by side for a clear and complete comparison. This table summarises every major difference between defining and non-defining relative clauses — keep it as your reference guide.