Relative clauses in English: when and how to use them correctly

29 January 2026

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English-learners

Oleksandra Kulish

Book expert

Relative Clauses are clauses that provide additional information about objects or situations in complex sentences.

For example:

I visited a museum that has amazing dinosaur exhibits. — I visited a museum that has amazing dinosaur exhibits.

The highlighted part of this sentence is the Relative Clause.

This material is devoted to all the nuances of using relative clauses in English and the rules for forming them. The grammar of Relative Clauses is quite simple, so we promise that the topic will be clear even for those who are just starting to learn English, and there will be no difficulties in mastering it.

Features of constructing sentences with Relative Clauses

The main function of Relative Clauses is to add details to the main information, creating a fuller picture of an object or situation. Therefore, relative clauses are usually placed at the end of a sentence or immediately after the noun they refer to.

The second important function of this structure is to emphasize a specific fact or detail.

A Relative Clause is a part of a sentence that contains additional information and includes a Relative Pronoun (for example: who, which, that).

Examples of the functions of Relative Clauses:

Additional information	Focus on the fact
My friend bought a guitar that has a unique design. — My friend bought a guitar that has a unique design.	These are the books which I recommended to you. — These are the books I told you about.
Our neighbors adopted a small kitten who loves to play. — Our neighbors adopted a small kitten who loves to play.	I noticed a bike that was left near the school gate. — I noticed a bike that was left near the school gate.

In the first column, the sentences provide additional information about an object or situation, while in the second column, they emphasize a specific fact that is important for understanding the context.

Relative Clauses: rules and types

In general, relative clauses are divided into two types:

Clauses that refer to the entire sentence or part of it — most often used in spoken language and less frequently in written language.
Clauses that refer to nouns or noun phrases.

To determine the type of a Relative Clause, it is useful to ask a question about the sentence.

Example 1 (refers to the whole sentence):

I spent the afternoon with my friend, which was really enjoyable. — I spent the afternoon with my friend, which was really enjoyable.

What was enjoyable? — The time spent with my friend. This is a Relative Clause that refers to the entire sentence.

Example 2 (refers to a noun or noun phrase):

I visited the museum on Saturday which had a fascinating dinosaur exhibition. — I visited the museum on Saturday that had a fascinating dinosaur exhibition.

What was fascinating? — The dinosaur exhibition. This is a Relative Clause that refers to a specific noun (museum).

Features of the first type

Which is always used, and it is preceded by a comma.
It is more common in informal speech to express personal opinions or evaluations.
In written language, it is used less often, but it helps emphasize the overall situation.

Examples:

My aunt decided to organize a picnic for her birthday, which will be really fun for everyone. — My aunt decided to organize a picnic for her birthday, which will be really fun for everyone.
Our team adopted a new working method, which has improved our efficiency. — Our team adopted a new working method, which has improved our efficiency.

Note: the part after which refers to all the preceding information or the general situation described by the sentence — this is the key feature of this type of Relative Clause.

Relative clauses that refer to nouns or noun phrases are further divided into two subtypes: Defining Relative Clauses, which identify a specific object necessary for understanding the sentence, and Non-defining Relative Clauses, which add extra information about a noun that is already clear from the context. Let’s look at them in more detail.

Defining Relative Clauses

Defining Relative Clauses are subordinate clauses that are placed immediately after the noun they describe. They can appear either at the end of a sentence or in the middle of it:

These are the students who participate in the science fair. — These are the students who participate in the science fair.
The chef who prepared this dish has won several awards. — The chef who prepared this dish has won several awards.

The following relative pronouns are used in Defining Relative Clauses: who, that, which, whose, whom, when, where.

In spoken English, that is often used instead of who, whom, or which:

We need volunteers that can help organize the event. — We need volunteers who can help organize the event.
Talk to teammates that have experience in project management. — Talk to teammates who have experience in project management.

Note: Defining Relative Clauses are not separated by commas in English.

If the relative pronoun functions as an object in the subordinate clause, it can be omitted:

This is the café (that) I love to visit on weekends. — This is the café I love to visit on weekends.
Here is the article (that) she recommended for the research. — Here is the article she recommended for the research.

In these examples, that can be omitted because it is the object (whom? what?).

Important: if the relative pronoun is the subject of the subordinate clause, it cannot be omitted:

The movie that inspired me is available online. — The movie that inspired me is available online.
The teacher who explains grammar clearly is very popular. — The teacher who explains grammar clearly is very popular.

So, if the relative pronoun is the subject, it must be kept; if it is the object, it may be omitted.

Non-defining Relative Clauses

The main difference between Non-defining Relative Clauses and Defining Relative Clauses is that the additional information is not essential for understanding the main meaning of the sentence. Such clauses are always separated by commas.

In other words, we can remove a Non-defining Relative Clause from a sentence, and this will not change its meaning or context:

Emma, who recently moved to Kyiv, opened a small café nearby. — Emma, who recently moved to Kyiv, opened a small café nearby.
The smartphone, which I bought last month, has already received a software update. — The smartphone, which I bought last month, has already received a software update.

In many cases, to determine whether the information is essential, you need to rely on the context of the text or conversation. This will help you decide whether commas are needed and whether a pause should be made in spoken language.

In such sentences, relative pronouns are always used and cannot be replaced with that. Only the following pronouns are used: who, which, whose, whom, where, when.

Punctuation rules and common mistakes in Relative Clauses

A common question is whether commas should be used or not. Here are the basic punctuation rules for relative clauses:

A comma is placed before which when the Relative Clause refers to the entire sentence rather than a specific noun.
Defining Relative Clauses are never separated by commas in written language.
Non-defining Relative Clauses are always separated by commas, and in spoken language, short pauses are made instead.

If it is difficult to determine whether a clause is Defining or Non-defining, focus on how important the additional information is for understanding the main meaning.

If the information is essential for identifying the noun, it is a Defining Clause.
If the information merely adds extra details without changing the core meaning, it is a Non-defining Clause.

Grammar does not always provide a strict answer, so rely on your understanding of the context and the logic of the sentence.