Relative Clauses: Who, Which, and That

Relative clauses let us add information about a person, thing or place without starting a new sentence. They make English more connected and help us avoid unnecessary repetition.

1. Who for people

Use who when the relative clause describes a person.

• The tutor who helped me was very patient.
• I know someone who works in education.

2. Which for things

Use which for objects, ideas and things.

• The book which I bought is useful.
• The lesson which we watched was short and clear.

3. That in defining relative clauses

In many defining clauses, that can refer to people or things.

• The app that we use is simple.
• The student that asked the question stayed after class.

In careful writing, who is often preferred for people, but that is common and natural in many defining clauses.

4. Defining information

A defining relative clause tells us exactly which person or thing we mean. It is necessary information, so we do not normally use commas.

The teacher who teaches Business English is from London.

The clause identifies which teacher.

5. Non-defining information

A non-defining relative clause adds extra information. It is separated by commas, and we normally use who or which, not that.

My tutor, who lives in Almaty, also teaches online.

We already know which tutor; the location is extra information.

6. When the relative word can disappear

If the relative word is the object of a defining clause, it can sometimes be omitted:

The book (that) I recommended is available online.

But if it is the subject, keep it: The book that explains the rule is useful.

Quick practice

Combine the sentences: (1) I met a tutor. She specialises in IELTS. (2) This is the resource. I mentioned it yesterday. (3) My laptop is five years old. It still works well.

Suggested answers: I met a tutor who specialises in IELTS. This is the resource (that/which) I mentioned yesterday. My laptop, which is five years old, still works well.