Practice
Commas in English: separate ideas without overusing them
A comma is a small mark, but one comma can help a reader see the parts of a sentence. The useful question is not where you would pause. It is what the words are doing.
Use commas to separate list items, set off an opening phrase, and join two complete ideas with a coordinating conjunction.
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
comma /ˈkɒm.ə/
The short answer
Use commas to separate items in a list, after an opening phrase when it helps the reader, and before a coordinating conjunction when it joins two complete sentences. Do not put a comma between a subject and its verb.
After lunch, we reviewed the schedule.
Why it works: The comma separates the opening time phrase from the main sentence.
5 more examples
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Please bring a notebook, a pen, and your ID card.
The commas separate three items with the same role in the list.
Not this:Please bring a
notebook and a pen. What changes: Two items joined by and do not normally need a comma. -
Before the interview, check the address and travel time.
The comma marks the end of the opening phrase before the main instruction begins.
Not this:Check the address
before the interview. What changes: The phrase comes after the main clause, so a comma is not needed here. -
Maya packed the samples, but she forgot the labels.
Both sides of but have a subject and verb, so the comma separates two complete ideas.
Not this:Maya packed the
samples but forgotthe labels. What changes: The subject Maya is shared, so the second part is not a complete sentence and the comma is not needed. -
The manager who called yesterday needs an answer.
The words who called yesterday identify which manager, so they stay closely connected to the noun without commas.
Not this:Our
manager, who called yesterday,needs an answer. What changes: Here the extra information is not needed to identify the manager, so commas set it off. -
The report from the finance team arrives tomorrow.
Do not put a comma between the subject report and the verb arrives.
Not this:The report from the finance
team, arrivestomorrow. What changes: This comma splits the subject from its verb, which makes the sentence harder to read.
Read the full guide
First, find the main subject and verb. Keep them together. Then look for a list, an opening phrase, or two complete ideas joined by words such as and, but, or so. Those structures can need a comma.
Separate items in a list
Use commas between three or more items that have the same role. The last two items are usually joined by and or or. A list can name things, actions, or descriptions.
The course covers reading, writing, speaking, and listening.
Use commas in a list of three or more items. With two items, and or or is usually enough: tea and coffee.
Where do the commas go: We need chairs tables lamps and shelves?
Write: We need chairs, tables, lamps, and shelves. Each noun is one item in the list.
Show where an opening phrase ends
An opening phrase gives time, place, condition, or background before the main sentence. A comma after a longer opening phrase helps the reader find the main subject and verb.
If the weather improves, we will eat outside.
On the way home, I stopped at the pharmacy.
If the weather improves, we will eat outside. The comma follows the opening condition. We will eat outside if the weather improves. The same condition follows the main clause, so no comma is needed.
Join two complete ideas carefully
A coordinating conjunction can join two complete sentences. The common conjunctions are for, and, nor, but, or, yet, and so. Put a comma before the conjunction when each side has its own subject and verb.
The train was delayed, so we called the office.
I wanted to attend, but I had a medical appointment.
Does this need a comma: Elena opened the file and checked the figures?
No. Elena is the subject of both verbs, so the second part is not a complete sentence on its own.
Do not split the core of a sentence
A comma should not separate a subject from its verb or a verb from its object. Find the basic pattern first: who or what does the action, what is the action, and what receives it? Keep those parts together.
The new assistant starts work on Monday.
The new assistant starts work on Monday is correct. The new assistant, starts work on Monday is not correct because the comma splits the subject and verb.
This check prevents many unnecessary commas. A pause in your voice is not enough reason to add one.
Set off extra information when it is extra
Some information adds a detail but does not identify the person or thing. Put that extra information between two commas. Do not use commas when the words are needed to say exactly which person or thing you mean.
My laptop, which is five years old, still works well.
The laptop that I bought last year still works well.
Which is five years old adds extra information about one known laptop. That I bought last year identifies a particular laptop, so it does not need commas.
Read the sentence without the words between commas. Does it still identify the same person or thing?
If the meaning still identifies the same person or thing, the detail may be extra information that commas can set off. Check the context before deciding.
Before you go
Remember this
Use commas to separate list items, to show where a useful opening phrase ends, and before a coordinating conjunction that joins two complete ideas. Keep a subject and its verb together. When you are unsure, identify the sentence structure before adding a mark.
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
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Try the written questionsQuestions about "Commas in English: separate ideas without overusing them"
When should I use a comma in English?
Use a comma to separate items in a list, after an opening phrase when it helps the reader, and before a coordinating conjunction that joins two complete ideas. Check what the words are doing before you add a comma.
Please bring a notebook, a pen, and your ID card.
Do I need a comma before and?
Use a comma before and when it joins two complete sentences, as in Maya packed the samples, and she sent them by courier. Do not normally use one when the subject is shared, as in Maya packed the samples and sent them by courier.
Please bring a notebook and a pen.
Why is there a comma after an opening phrase?
A comma can show where background information ends and the main sentence begins. For example, After the meeting, I wrote the summary makes the opening time phrase easy to separate from the main action.
Before the interview, check the address and travel time.
Can I put a comma wherever I pause?
No. Speakers pause for many reasons, and those pauses do not always match sentence structure. Do not split a subject from its verb, as in The report from the finance team arrives tomorrow.
Check the address before the interview.
What is the Oxford comma?
The Oxford comma is the final comma before and or or in a list of three or more items. Some styles use it and some do not. Follow the style required by your school, workplace, or publication and use it consistently.
Maya packed the samples, but she forgot the labels.
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