Mastering Relative Clauses in English: who, which, and that (B1)

Relative clauses are like little bridges that connect ideas. They help you add useful details to a person, thing, or idea without starting a new sentence: “the woman who lives upstairs,” “the movie that we watched,” “the phone which I bought.” In this post, you’ll learn when to use who, which, and that, how commas change meaning, and how to sound natural in everyday conversation.

English
The man who lives next door is a chef.
A man lives next door; he is a chef. The clause gives more detail about “the man.”
English
I loved the book that you recommended.
You recommended a book; I loved it. The clause describes “the book.”
relative clause
a clause that describes a noun
noun
The car that I bought is electric.
A clause adds info about “the car.”
defining clause
essential information; no commas
noun
Students who study daily improve fast.
The clause identifies which students.
non-defining clause
extra information; use commas
noun
My brother, who lives in Rome, is visiting.
The clause is extra; it uses commas.
pronoun (relative)
word like who/which/that that introduces a relative clause
noun
The movie which won the award was fantastic.
“Which” introduces the clause.

Who, which, or that?

  • Use who for people.
    • “The teacher who explained the rule was patient.”
  • Use which for things and animals.
    • “The laptop which I bought is fast.”
  • Use that for people or things in defining clauses (very common in speech).
    • “The friend that I met yesterday is from Brazil.”

In everyday English, that often replaces who or which in defining clauses (no commas). In non-defining clauses (with commas), we usually use who or which, not that.

The person called you is my manager.

The man which lives next door is a doctor. → The man who lives next door is a doctor. Use “who” for people, especially as the subject of the clause.
🧠 Choose the best relative pronoun

Defining vs. non-defining (commas matter!)

  • Defining clauses identify which person or thing you mean. No commas.
    • “The students who arrive early get extra practice.” (Which students? The ones who arrive early.)
  • Non-defining clauses add extra information about a person or thing that is already clear. Use commas.
    • “My boss, who started the company, is very creative.” (We already know which boss; the clause is extra.)

Changing commas can change meaning:

  • “My phone that is new is fast.” (I have more than one phone; the new one is fast.)
  • “My phone, which is new, is fast.” (I have one phone; extra info: it’s new.)
English
The museum, which opened last year, has a new café.
Extra info about the museum; use commas and which.
English
The people who live here are friendly.
Defining: identifies which people.

This is the book I was telling you about.

🔠 Put the words in order

Start with The + noun, then the relative clause.

When can you drop the pronoun?

If the relative pronoun is the object of the clause, you can often leave it out in defining clauses:

  • “The book (that/which) I read was excellent.” → “The book I read was excellent.”
  • “The restaurant (that/which) we chose is cheap.” → “The restaurant we chose is cheap.”

You cannot drop the pronoun when it’s the subject of the clause:

  • “The teacher who helped me was kind.” → You must keep who (subject).
The project I worked on was difficult, which I finished late. → The project I worked on was difficult, so I finished late. Use a connector like “so” for cause/effect. “Which” should describe a noun, not a whole idea here at B1 level.
💬 At the café
non- prefix (not) defin(e) root (to set/describe) -ing suffix (forming adjective)

Cultural note: tone and formality

  • In everyday speech, “that” is very common: “The guy that works here is helpful.”
  • In formal writing, “which” is preferred for things, especially in non-defining clauses with commas: “The policy, which was updated in 2024, affects all employees.”
  • “Whom” exists but is rare in conversation. At B1, you can usually use who instead: “The person who I spoke to…” is fine in spoken English.

Small style tip: In formal English, some writers avoid “that” for people (“the person that…”) and use “who” instead. In everyday speech, “that” for people is acceptable: “the friend that I met.”

Quick practice: spot the meaning

  • “Neighbors who have dogs often meet in the park.” → Defining (which neighbors?)
  • “My neighbors, who have dogs, often meet in the park.” → Non-defining (extra info; we already know the neighbors)

Try saying both aloud and notice how the commas create a pause and a different meaning.

Wrap-up

You’ve seen how relative clauses work and how to choose who, which, and that:

  • who → people (especially subject)
  • which → things/animals (especially formal or with commas)
  • that → people or things in defining clauses (very common in speech)

Remember the comma rule: non-defining clauses use commas and usually who/which, not that. In defining clauses, you can often drop the object pronoun to sound natural: “The song (that) I like is trending.”

Keep practicing by describing real things around you:

  • “The friend who messaged me…”
  • “The café that we visited…”
  • “The jacket which I bought last week…”

Speak, write, and notice the commas—they change meaning! You’ve got this.