The key idea
Choose a defining clause for necessary information and a non-defining clause for extra information, then punctuate each correctly.
What is it for?
Learn to add clear, useful details about people and places without writing too many separate sentences.
What you need to know
- Use defining clauses to identify a person, place, or thing.
- Use non-defining clauses to add extra information between commas.
- Choose who, which, that, where, or whose to connect ideas.
- Use whom or a final preposition when the sentence needs it.
- Keep each sentence focused on no more than two main ideas.
1. Use defining clauses to identify someone or something
A defining clause tells readers exactly which person or thing you mean.
Do not use commas around this clause. Choose the linking word that fits the meaning.
- Use who for people.
- Use that or which for things.
- Use where for places.
- Use whose to show possession.
- Do not put commas around defining clauses.
The woman who runs the bakery knows my family.
Who identifies the woman.
I prefer the room that faces the garden.
That identifies the room.
We visited the café where my uncle works.
Where connects the place with an activity.
She hired a cook whose meals impressed everyone.
Whose shows that the meals belong to the cook.
2. Use non-defining clauses for extra information
A non-defining clause adds information about someone or something already identified.
Put a comma before and after the clause when it sits inside a sentence. Use which, who, or whose, not that.
- Use commas to separate extra information.
- Use who for extra details about people.
- Use which for extra details about things.
- Use whose to add information about possession.
- Do not use that in a non-defining clause.
My aunt, who lives nearby, runs a small shop.
The commas mark extra information about my aunt.
The shop, which opened last year, sells fresh bread.
Which adds a detail about the shop.
Our neighbour, whose dog often visits us, grows tomatoes.
Whose connects the neighbour with the dog.
3. Choose the right form with people and prepositions
Sometimes a clause needs a word such as to, with, or for.
In formal writing, a preposition can come before whom. In everyday writing, it often stays at the end.
- Use whom after a preposition in formal writing.
- Use who in many everyday clauses about people.
- Keep a final preposition when it sounds more natural.
- Do not use whom for things.
The manager to whom I spoke offered useful advice.
To whom is formal.
The manager who I spoke to offered useful advice.
The final to is natural in everyday writing.
This is the friend with whom I share an office.
With whom suits a formal style.
4. Use which to connect a result or reaction
Which can refer to a whole idea from the previous clause.
Use a comma before which. This helps readers see the result or reaction clearly.
- Put a comma before which.
- Use this pattern to show a result or reaction.
- Do not use that to refer to the whole previous idea.
- Keep the sentence short enough to follow easily.
The bus arrived forty minutes late, which upset the passengers.
Which refers to the late arrival.
The café had closed early, which surprised our group.
Which refers to the early closing.
5. Join ideas without making sentences too long
Relative clauses help you combine related details. First, write the main idea. Then add one useful detail about a person, place, or thing.
Before joining ideas, check that the extra detail belongs to the main idea. Two main ideas are usually enough for one sentence.
- Find two ideas about the same person, place, or thing.
- Choose a linking word that matches the meaning.
- Check whether the detail is necessary or extra.
- Add commas only when the clause gives extra information.
- Split the sentence if readers may lose the main point.
The library, which overlooks the river, stays open until nine.
The relative clause adds one clear detail.
I met a baker who makes excellent bread.
The defining clause identifies the baker.
How to do it, step by step
- Name the person, place, or thing you want to describe.
- Choose one related detail that helps readers understand it.
- Decide whether the detail identifies it or simply adds information.
- Choose the correct relative word and add commas if needed.
- Read the sentence again and remove any unnecessary detail.
Formulas and key language
| Use it for | Example | Another example |
|---|---|---|
| person + who + verb | I know a teacher who speaks three languages. | We hired a guide who knows the area. |
| thing + that/which + verb | She bought a phone that takes clear photos. | We use a machine which saves time. |
| place + where + subject + verb | This is the park where we exercise. | I remember the town where my father grew up. |
| person/thing + whose + noun + verb | I met a woman whose son studies abroad. | They rent a house whose windows face south. |
| name, who + extra information, + main verb | Lina, who works nearby, visits us weekly. | My uncle, who enjoys cooking, prepares Sunday lunch. |
| thing, which + extra information, + main verb | The oven, which we bought recently, works well. | The road, which crosses the valley, is narrow. |
| main clause, which + result | The shop was closed, which disappointed the customers. | Our train stopped suddenly, which delayed our arrival. |
| person + preposition + whom | The colleague to whom I wrote replied quickly. | The customer with whom I spoke seemed satisfied. |
| person + who + subject + verb + preposition | The colleague who I wrote to replied quickly. | The customer who I spoke with seemed satisfied. |
UK / US: British and American English both use these relative clauses. In everyday writing, both often allow who or that for people in defining clauses. Formal writing may prefer whom after a preposition.
Level up: Replace basic words (good, very, nice) with stronger ones. See our A2 to B2 upgrades page.
Model text
A Place Worth Visiting
Introduction
Greenfield Market is a lively place where local families buy fresh food. It stands beside the old library, which was built more than a century ago. The market attracts visitors who enjoy homemade products and friendly service.
Where identifies the place for shopping. Which adds extra information about the library. Who identifies the visitors.
The place
The market has several stalls that sell vegetables, bread, and handmade gifts. My favourite is a small bakery whose owner prepares everything before sunrise. The bread, which is made with local flour, usually sells out before lunchtime. Last Saturday, the electricity failed for an hour, which delayed several orders. The staff stayed calm and served customers by the front window.
That identifies the stalls. Whose shows ownership. Which adds details about the bread and explains the result of the power failure.
The person
Marta, who has managed the bakery for eight years, knows many customers by name. She is the person to whom new workers turn for advice. She also supports a local food project that helps families in need. What I admire most is her patience, which makes busy mornings easier for everyone. The market is more than a shopping place because people like Marta help the community stay connected.
Who adds information about Marta. To whom is formal, while that identifies the project. Which refers to her patience. The final sentence explains the market's wider value.
Common mistakes
✗ My sister, that works nearby, visits every Friday.
✓ My sister, who works nearby, visits every Friday.
Use who, not that, in a non-defining clause.
✗ The shop which sells fruit, is always busy.
✓ The shop which sells fruit is always busy.
Do not add a comma inside a defining clause.
✗ Our neighbour who owns the café, is very helpful.
✓ Our neighbour, who owns the café, is very helpful.
The extra information needs a comma before and after it.
✗ I visited the village which my grandmother grew up.
✓ I visited the village where my grandmother grew up.
Use where to refer to the place of an activity.
✗ The train was cancelled, that annoyed the passengers.
✓ The train was cancelled, which annoyed the passengers.
Use which to refer to the whole previous idea.
✗ The woman whose I met owns the shop.
✓ The woman whom I met owns the shop.
Use whom as the object of met, not whose.
Plan it, then check it
Plan
- Choose a place and a person connected to it.
- Write the main fact about each one.
- Add details using at least three relative clauses.
- Mark each clause as defining or non-defining.
- Arrange the details so the description feels clear and natural.
Check
- Check that every relative word matches its meaning.
- Check commas around non-defining clauses.
- Check that defining clauses have no extra commas.
- Check that you use which for a whole previous idea.
- Split any sentence that carries too many details.
Practice
Choose the correct clause
Choose the option that completes each sentence correctly.
1.The man ___ repairs our bicycles lives nearby.
Who identifies the man, so no comma is needed.
2.My flat, ___ overlooks the park, gets plenty of sunlight.
Which introduces extra information about the flat.
3.We visited the village ___ my mother was born.
Where refers to the place of her birth.
4.The woman ___ car was stolen reported it immediately.
Whose shows that the car belongs to the woman.
5.The restaurant was closed, ___ disappointed our guests.
Which refers to the whole situation before the comma.
6.My cousin, ___ works at the hospital, lives nearby.
Who adds extra information about a person.
Complete the relative clause
Write who, which, whose, or where in each gap.
1.The nurse helped my father was patient.
Who refers to a person who performed the action.
2.I found the keys you left them.
Where shows the place where the keys were left.
3.The film we watched last night was moving.
Which refers to the film.
4.We met a farmer daughter studies medicine.
Whose shows that the daughter is related to the farmer.
5.The café serves fresh soup is always busy.
Which introduces a defining clause about the café.
6.The neighbour checks our mail is away this week.
Who identifies the neighbour.
Build sentences with relative clauses
Put the words in order. Add the correct punctuation.
1.Put the words in order:
nearbyauntmywomanwhoistheworks
The defining clause identifies which woman is meant.
2.Put the words in order:
mythewhichquietisoverlooksflatgarden
The commas show that the clause adds extra information.
3.Put the words in order:
thebakerypopularbreadsellsownerisfreshwhose
Whose connects the bakery with its owner.
4.Put the words in order:
nearbyweisthewhereexercisepark
Where connects the park with the activity.
5.Put the words in order:
annoyedeveryonethewhicharrivedlatebus
Which refers to the late arrival.
Correct one small mistake
Correct the single mistake in each sentence.
1.The baker, that works here, is friendly.
Use who in a non-defining clause about a person.
2.The house, that stands near the river, is empty.
Use which, not that, in a non-defining clause about a thing.
3.The boy who lives next door, plays tennis.
A defining clause does not need a comma before the main verb.
4.My aunt, who lives in Madrid visits us yearly.
The extra information needs a closing comma.
5.The road was flooded, that delayed our trip.
Which refers to the whole situation before the comma.
6.The woman whose I called answered quickly.
Whom or who can be the object of called, but whose shows possession.
Now write
Your task
Write a short article about a place and a person you know. Use made-up details to protect your privacy. Describe the place first, then introduce the person. Include at least three relative clauses. Use defining clauses to identify people or things. Use non-defining clauses to add extra details. Check your commas before finishing. Draft idea: A local community centre has a busy kitchen and a small garden. A volunteer named Elena organises its weekly activities. The centre also offers free classes for local families. Describe how the place works and why Elena matters to the community.
Word bank
community centrequiet streetlocal marketwelcoming atmosphereexperienced workerregular visitorswell-known cafénearby parkhelpful neighbourweekly activitiesfresh ingredientsshared workspacereliable servicelocal families
Sentence starters
- The place I want to describe is ...
- It is a place where ...
- The person who makes a difference is ...
- One feature that attracts visitors is ...
- The building, which ..., also ...
- What I appreciate most is ...