Relative Clauses with *who*, *which*, and *that* in English

In Brief

A relative clause describes or identifies a noun: the neighbour who plays the piano or the phone that I bought. Use who for people, which for things, and that for either people or things in an essential, identifying clause. Do not put commas around information that is needed to identify the noun.

Overview

A relative clause is a group of words that describes a noun (a word for a person, place, thing, or idea). It lets you combine two related thoughts without repeating the noun. Instead of I met a woman. The woman designs bridges, you can say I met a woman who designs bridges.

At A2, the most useful pattern is the defining relative clause: a clause that tells the listener exactly which person or thing you mean. In Where is the key that opens this door?, the words that opens this door identify the key. This information is essential, so there is no comma.

The relative words who, which, and that connect the description to the noun before it. That noun is called the antecedent (the person or thing that the relative word refers back to). The basic choice is simple: who refers to people, which to things, and that can replace either one in defining clauses. Later sections explain object omission, commas, and more formal choices.

How It Works

Choosing the relative word

Noun being described	Usual choice	Also possible in a defining clause	Example
person or people	who	that	the nurse who/that helped me
thing, animal, or idea	which	that	the bag which/that disappeared

For people, who is often the clearest and most natural choice. That is also normal when the clause identifies the person: the person that called. For things, both which and that are common in defining clauses, although preferences vary by region and style.

Animals can be treated in two ways. Use which or that when simply describing an animal as an animal: a bird that cannot fly. People often use who for a named pet or an animal presented as an individual: our dog, who hates rain.

The basic sentence pattern

A defining relative clause normally comes immediately after the noun it describes:

noun + who/which/that + relative clause

• the student who sits by the window
• a film that we watched last night
• the information which you requested

Do not move the relative clause to the end if that makes its noun unclear. I bought a jacket yesterday that has silver buttons can be understood, but I bought a jacket that has silver buttons yesterday more clearly keeps the description beside jacket.

When the relative word is the subject

The subject is the person or thing that performs the action or is in the stated condition. In the woman who works here, who is the subject of works. A subject relative word must remain in the sentence.

noun + who/which/that + verb

• the driver who stopped
• a machine which saves energy
• the bus that goes downtown

The verb agrees with the noun before the relative clause. Agreement means that the verb form matches singular or plural:

• the employee who works at reception
• the employees who work at reception

Do not add another subject pronoun after the relative word. Say the man who lives upstairs, not the man who he lives upstairs. Here, who already means “the man” inside the clause.

When the relative word is the object

The object is the person or thing affected by the action. In the woman who I called, I is the subject, and who is the object of called.

noun + who/which/that + subject + verb

• the colleague who I invited
• the recipe which Maya recommended
• the shoes that he ordered

In a defining clause, an object relative word can often be omitted:

• the colleague I invited
• the recipe Maya recommended
• the shoes he ordered

This is sometimes called a zero relative because there is no visible relative word. Omission is not possible when the relative word is the subject: the colleague works with me is a complete main clause, but it cannot mean the colleague who works with me inside a larger noun phrase.

A quick test is to look directly after the relative word. If a new subject such as I, Maya, or he follows, the relative word is probably the object and may be omitted. If a verb follows immediately, the relative word is probably the subject and must stay.

Defining clauses do not use commas

A defining clause identifies which noun you mean:

• Employees who work at night receive an extra payment.

This means the night employees receive it; the clause selects a particular group. Do not separate this essential information with commas. Commas signal a different type of relative clause, covered below under advanced use.

Examples in Context

English	Meaning in plain English	Note
The man who lives next door is a doctor.	The man living beside us is a doctor.	Who is the subject and refers to a person.
People who work hard often improve quickly.	Hard-working people often make fast progress.	Plural people takes work, not works.
Is she the teacher that runs the evening class?	Is she the teacher responsible for that class?	That refers to a person in a defining clause.
I need a laptop which can run this program.	I need a laptop capable of running this program.	Which is the subject and refers to a thing.
The bus that stops outside goes to the airport.	The airport bus is the one stopping outside.	The clause identifies the bus.
The book which I bought is on the desk.	The book I purchased is on the desk.	Which is the object of bought.
The car that I want is too expensive.	My preferred car costs too much.	That is an object relative word.
The car I want is too expensive.	My preferred car costs too much.	The object that has been omitted.
Have you seen the keys that were on the table?	I mean the keys previously lying on the table.	Passive were follows subject that.
She is someone who always remembers birthdays.	She never forgets people’s birthdays.	Who is natural for a person.
The meal we ordered has not arrived yet.	Our ordered meal is still missing.	Zero relative: omitted object that/which.
I spoke to the technician who you recommended.	I spoke to your recommended technician.	Object who could be omitted.

Common Mistakes

Adding a second subject

• Wrong: The woman who she called me was polite.
• Right: The woman who called me was polite.
• Why: Who is already the subject of called. English does not add she as a second subject.

Omitting a subject relative word

• Wrong: The train leaves at six is usually crowded.
• Right: The train that leaves at six is usually crowded.
• Why: That performs the action leaves, so it is a subject and cannot be omitted.

Using which for a person

• Wrong: The friend which helped me lives nearby.
• Right: The friend who helped me lives nearby.
• Why: Use who for a person. That is also possible here, but who sounds more personal and is usually preferred.

Repeating the object

• Wrong: This is the phone that I bought it yesterday.
• Right: This is the phone that I bought yesterday.
• Why: That already represents the phone as the object of bought. Do not repeat it with it.

Using singular agreement after a plural noun

• Wrong: People who works from home need reliable internet.
• Right: People who work from home need reliable internet.
• Why: The verb agrees with plural people, not with the unchanging word who.

Putting commas around identifying information

• Wrong: The students, who need help, should stay after class. (if only some students need help)
• Right: The students who need help should stay after class.
• Why: Without commas, the clause identifies which students should stay. With commas, the sentence suggests that all the students need help.

Usage Notes

In everyday speech, English speakers frequently omit an object who, which, or that: the person I met, the song we heard. Keeping the word is equally grammatical and can make a long sentence easier to follow. Subject relative words are never omitted in standard English.

For defining clauses about things, both the file which I sent and the file that I sent are standard. That is especially frequent in conversation and is often recommended in American edited prose for defining clauses. British usage readily allows defining which. This is a style preference, not a universal rule of grammatical correctness.

A relative clause can describe indefinite words such as someone, anyone, something, everything, and nothing. Who is usual after words for people: someone who understands. That is very common after words for things, especially everything, something, and nothing: everything that matters.

Beyond the Basics / Advanced Use

You do not need to master all of the following at A2, but you will often meet these patterns in reading and careful speech.

Extra information: non-defining clauses

A non-defining relative clause adds extra information rather than identifying the noun. It is separated by commas in writing and by a slight pause in speech:

• My brother, who lives in Leeds, is visiting tomorrow.
• This camera, which I bought in 2020, still works well.

The listener already knows which brother or camera is meant. The clause simply adds a fact. Use who for people and which for things in this pattern; do not use that. The relative word also cannot be omitted.

Compare the meanings:

Defining	Non-defining
My cousins who live in Canada are visiting.	My cousins, who live in Canada, are visiting.
Only the cousins in Canada are visiting.	All the cousins being discussed live in Canada and are visiting.

Whom and prepositions

Whom is the formal object form for people. It is uncommon in relaxed conversation, where who or no relative word is more natural:

• formal: The candidate whom we interviewed was excellent.
• neutral: The candidate who we interviewed was excellent.
• conversational: The candidate we interviewed was excellent.

After a preposition placed before the relative word, formal English uses whom for people and which for things:

• the client to whom I wrote
• the project on which we worked

In ordinary speech, the preposition usually moves to the end: the client (who) I wrote to; the project (that) we worked on. That cannot directly follow a fronted preposition: not the project on that we worked.

Referring to a whole idea with which

A non-defining which clause can comment on an entire earlier statement:

• The meeting ended early, which surprised everyone.

Here, which does not mean only the meeting. It refers to the whole fact that the meeting ended early. That cannot be used this way.

Reduced relative clauses

More advanced English sometimes shortens a relative clause:

• the people waiting outside = the people who are waiting outside
• the documents sent yesterday = the documents that were sent yesterday

These are called reduced relative clauses because part of the full clause has been removed. Learn the full forms first; they make the shorter patterns easier to understand.

Practice Tips

1. Combine pairs of sentences. Start with I know the woman. She owns the café. Then write I know the woman who owns the café. Decide whether the repeated noun is a person or thing before choosing the relative word.
2. Mark subject and object relatives. In a short text, underline the noun and circle who, which, or that. If a verb comes next, label it “subject”; if a new subject comes next, label it “object” and test whether omission works.
3. Practise the comma contrast aloud. Compare the guests who arrived early with the guests, who arrived early, and explain whether the clause selects some guests or adds information about all of them.

Related Concepts

• Prerequisite: Subject Pronouns — helps you recognise who or what is the subject inside a relative clause.
• Next steps: Relative Clauses: where, when, whose — adds relative words for places, times, and possession, and develops non-defining clauses further.