Practice
That and which: choose the right relative word
Sign in to saveCompare these two messages: ‘The files that need signatures are on my desk.’ ‘The files, which need signatures, are on my desk.’ The commas change what the writer says about the files.
Choose that or which by deciding whether a relative clause identifies the noun or adds extra information, and use commas to show the difference.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
The report that I referred to is attached. /ðə rɪˈpɔːt ðæt aɪ rɪˈfɜːd tuː ɪz əˈtætʃt/
The short answer
Use a defining relative clause, usually without commas, when the clause identifies the person or thing. In American edited prose, that is a common choice for this use. Use which with commas when the clause adds extra information. British usage also allows which in many defining clauses, so follow the style expected by your reader.
The phone that is charging belongs to Nia.
Why it works: The clause identifies one phone among several, so it has no commas.
5 more examples
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The bus that stops at the library is late.
The clause tells the reader which bus is late.
Not this:The number 18 bus,
which stops at the library, is late. What changes: The route number already identifies the bus. Its stop is extra information. -
Please return the forms that have a blue sticker.
Only the forms with blue stickers should be returned, so the clause limits the group.
Not this:Please return the forms,
which have blue stickers. What changes: This says that all of the forms have blue stickers and asks for all of them to be returned. -
The report that I referred to is attached.
That can introduce a defining clause when the preposition stays at the end.
Not this:The report
to which I referredis attached. What changes: This is a more formal version with the preposition before which. -
My laptop, which I bought last year, needs a new battery.
My laptop already identifies the noun. The purchase date is an added comment.
Not this:The laptop
that I bought last yearneeds a new battery. What changes: The clause identifies one laptop and has no commas. -
The gallery, which opens at noon, is near the station.
The clause adds a detail about an already identified gallery.
Not this:The gallery
that opens at noonis near the station. What changes: The clause chooses one gallery from a possible group of galleries.
Read the full guide
A relative clause comes after a noun and gives more information about it. The useful first decision is whether you can remove the clause without changing which thing the sentence refers to. If removing it leaves the reader unsure, the clause is defining. If the noun is already clear, the clause may be non-defining and should be set off with commas.
Decide whether the clause identifies the noun
A defining clause helps the reader pick the right person or thing from more than one possibility. Without it, the noun would be too broad. Do not put commas around this kind of clause.
The keys that are on the counter are mine.
The clause identifies the keys on the counter. It does not comment on every key in the room.
Does the clause in this sentence help you choose a particular set of keys?
Yes. It tells you which keys belong to the speaker, so there are no commas.
Use commas for extra information
A non-defining clause gives an extra fact about a noun that is already clear in the conversation or sentence. Put commas around the clause, and use which for things. If you remove the clause, the main reference should stay clear.
Our office, which is on the third floor, opens at eight.
Our office is already identified. The floor is useful information, but it does not select one office from several.
What happens if you remove ‘which is on the third floor’ from this sentence?
The sentence still tells you when the office opens, so the clause is extra information.
See how commas change the message
Commas can change the group that a sentence describes. This matters in instructions, emails, and reports. Before you write, ask whether the detail applies to every item or only to a selected group.
Employees who work on Fridays receive the update.
Without commas, the update goes to the employees who work on Fridays, not necessarily to every employee.
Employees, who work on Fridays, receive the update.
With commas, the writer presents working on Fridays as a fact about all of the employees.
Follow the style expected by your reader
In American edited writing, that is often preferred in a defining clause about a thing. Which is normally kept for clauses with commas. In British English, which may also appear without commas in a defining clause. Both varieties use which with commas for a non-defining clause.
American style: The policy that applies to visitors is on the website.
The clause identifies one policy, so that is a clear American-style choice.
British usage: The policy which applies to visitors is on the website.
This can be acceptable in British usage because the clause still identifies the policy and has no commas.
Place prepositions carefully
When a preposition comes before the relative word, choose which, not that. This structure is common in formal writing. In ordinary conversation, many speakers leave the preposition at the end, where that can work in a defining clause.
The colleague with whom I spoke sent the details.
With whom is formal. The preposition comes before whom, so that cannot replace it in this position.
The report that I asked about is ready.
About stays at the end, so that can introduce the defining clause.
Check the sentence by removing the clause
A quick removal check can help when you are unsure. Take out the relative clause and read the sentence again. If the noun becomes unclear, you probably need a defining clause without commas. If the sentence still names the same person or thing, the clause is likely extra information.
The café that serves breakfast opens at seven.
Without the clause, the reader may not know which café opens at seven. The clause is defining.
Remove the clause from ‘My neighbor's café, which serves breakfast, opens at seven.’ Is the café still identified?
Yes. My neighbor's café identifies it, so the breakfast detail can be placed between commas.
Before you go
Remember this
First, decide whether the clause answers ‘which one?’ If it does, write a defining clause without commas and choose that when an American-style rule calls for it. If the noun is already clear, use which with commas for extra information. Read the sentence once without the clause to check that your punctuation matches the meaning.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "That and which: choose the right relative word"
What is the main difference between that and which?
The main difference is often the job of the relative clause. Use a defining clause to identify which thing you mean, and use a non-defining clause to add information about a thing already identified. In American edited prose, that is common in defining clauses and which is used with commas for added information.
The phone that is charging belongs to Nia.
Do I need commas with that and which?
Use commas around a non-defining clause because it gives extra information. Do not use commas around a defining clause because it identifies the noun. Read the sentence without the clause: if the reference becomes unclear, the clause usually needs no commas.
Nia's phone, which is charging, is on the shelf.
Can I use which without commas?
Yes, which can introduce a defining clause in British usage. In American formal style, many editors prefer that for a defining clause about a thing. Follow the style guide for the document, but keep the meaning and comma pattern clear.
The bus that stops at the library is late.
Can that follow a preposition?
Do not place that directly after a fronted preposition. Use which in a formal phrase such as ‘the subject about which we spoke.’ In a defining clause, you can often move the preposition to the end and write ‘the subject that we spoke about.’
The number 18 bus, which stops at the library, is late.
Is the rule the same for people?
For people, who is usually the clearest relative word, especially in non-defining clauses. That can appear in some defining clauses about people, but who is often the better choice when you want a direct, neutral sentence. Use commas when the clause adds extra information.
Please return the forms that have a blue sticker.