Extra information: who and which between commas
Short answer: Extra information gives a fact about a person or thing that we already know. Put it between two commas and start it with who for a person or which for a thing: Ben, who lives next door, is my friend. Our school, which is very old, has a big garden. Never use that between commas. The sentence still makes sense without the extra part.
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At a glance
| Type | Word | Example |
|---|---|---|
| extra fact about a person | , who ... , | Ben, who lives next door, is my friend. |
| extra fact about a thing | , which ... , | Our school, which is very old, has a big garden. |
| needed information | no commas | The girl who has a kite is my sister. |
In short
- Extra information goes between two commas.
- who for people, which for things.
- Never that between commas.
What is the rule for “Extra information with commas”?
The rule
Extra information stands between two commas, with who (people) or which (things).
How it looks
, who + extra information , · , which + extra information ,
What it means
The sentence is complete without it. It only gives more facts.
When to use it
Use it when we already know which person or thing, and you add a fact.
How it works
- Is the person or thing already clear? Then the clause gives only extra information.
- Put one comma before who or which and one after the extra information.
- Use who for people and which for things. Never use that here.
- If you take the extra part out, the sentence must still be complete.
Examples of “Extra information with commas”
- Ben, who lives next door, is my friend.
Ben is a person: who. - Our school, which is very old, has a big garden.
A school is a thing: which. - My uncle, who is a doctor, works at night.
Extra fact about my uncle. - The girl who has a kite is my sister.
Needed information: no commas. - Hanoi, which is the capital, is a busy city.
Extra fact about a city. - My teacher, who is from Hue, speaks very clearly.
Extra fact about my teacher. - The film, which I saw last night, was too long.
Extra fact about the film. - Mia, who is ten, plays the violin.
Extra fact about Mia.
Common mistakes with “Extra information with commas”
My dog, that is brown, likes milk.→ My dog, which is brown, likes milk.
Between commas never use that.My brother who is ten plays basketball.→ My brother, who is ten, plays basketball.
Extra information needs a comma at both ends.My bike, who is red, is old.→ My bike, which is red, is old.
A bike is a thing: which.My sister, who she is a nurse, works nights.→ My sister, who is a nurse, works nights.
Do not repeat the pronoun after who.Paris, which is the capital of France is beautiful.→ Paris, which is the capital of France, is beautiful.
Close the extra information with a second comma.
Exceptions: watch out
- Two commas
Put one comma before who / which and one after the extra information. If it comes at the end of the sentence, the full stop is the second mark.
Needed information and extra information
Needed information tells which one you mean and has no commas. Extra information adds a fact and has two commas.
| Type | Example | Commas |
|---|---|---|
| needed | My brother who is ten plays basketball. (I have more than one brother) | none |
| extra | My brother, who is ten, plays basketball. (I have one brother) | two |
See also: Describing people with who
Check yourself
- Add commas: “Ben who lives next door is my friend.”
Show the answer
Ben, who lives next door, is my friend. Extra information needs two commas.
- Choose: “My bike, ___ is red, is old.” (who / which)
Show the answer
which A bike is a thing.
- Fix: “My dog, that is brown, likes milk.”
Show the answer
My dog, which is brown, likes milk. Never use that between commas.
How to practice “Extra information with commas”
The interactive version adds step-by-step help, spoken instructions and a quick check. One rule card, one sound lesson and the first lesson of every stone are free to try; the rest is part of Full Access. See Full Access.
- Practice lesson: Extra information with commas: who and which
Questions
How do I know whether to use commas?
Ask: does the clause tell me which one, or only add a fact? If I already know which one, add commas.
Why not “that” between commas?
That is used for needed information. In extra information, English uses who or which.
Can the extra part be at the end?
Yes: I met Ben, who lives next door. The full stop is the second mark.
More Texts and Talk rules
- Have you ever …? Experience: have / has + the past form tells about something you did (or never did) in your life, up to now.
- already, yet, just: already, yet and just go with have / has and tell about things that happened a short time ago.
- Present perfect or past simple?: A finished time (yesterday, last week) needs the past simple. Experience up to now needs have + the past form.
- Advice and rules: should, must, have to: should gives advice. must and have to give rules. After them, use the plain action word.
- unless: unless means if not. It says what could stop something.
- as … as, and comparing actions: as … as says two things are the same. not as … as says one is less. For actions use faster or more carefully.
Used in these writing topics
Part of the 📘 Grammar tool. Level G6: Texts and Talk. Đọc bằng tiếng Việt.
Written for English learners by the English for Fun team. How we write our lessons · Last updated 2026-11-05.
Reviewed by Chinh Q. Hoang, PhD, founder, English for Fun · 2026-10-30
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