Commas

A2 · ElementaryPunctuation

Lists, joined clauses, introductory phrases, and extra information — the comma's main jobs, and the comma splice to avoid.

What you'll learn

  • Use a comma to separate items in a list: apples, bananas, and oranges
  • Use a comma before a coordinating conjunction (and, but, so, or) joining two full sentences
  • Use a comma after an introductory word or phrase: After the meeting, we went home
  • Use commas around extra, non-essential information: My brother, who lives in Kyiv, is visiting
  • English does NOT normally use a comma before 'that' or 'because' introducing essential information

What commas do

A comma marks a short pause or separation within a sentence — much shorter than a full stop. English uses commas in a handful of specific, learnable situations: separating list items, joining two full sentences with a conjunction, setting off an introductory phrase, and marking extra information that could be removed without changing the sentence's basic meaning.

"I bought apples, bananas, and oranges."
"After the meeting, we went home."

Lists and joining two sentences

In a list of three or more items, use a comma after each item (the comma before 'and' — the Oxford comma — is optional but common and always safe to use). When joining two full sentences with a coordinating conjunction (and, but, so, or, yet), put a comma before the conjunction.

"I bought apples, bananas, and oranges."
"I was tired, but I kept working."
"It was raining, so I stayed inside."

Introductory phrases and extra information

Use a comma after an introductory word or phrase that comes before the main clause: After the meeting, we went home. However, I still disagree. Use a pair of commas around extra information that could be removed without changing the sentence's core meaning — this is often a non-defining relative clause.

"After the meeting, we went home."
"My brother, who lives in Kyiv, is visiting."

Where English does NOT use a comma

English does not normally put a comma before 'that' introducing a reported statement (She said that she was tired — no comma), and does not normally put a comma before 'because' when it introduces the main reason for something (I stayed home because I was sick — no comma). This surprises many learners, since some other languages punctuate these more heavily.

"She said that she was tired."
"I stayed home because I was sick."

Real English

"After a long day, I just want to relax."
"I like tea, but I love coffee."
"My sister, who works in London, is visiting next week."
"It was cold, so we lit a fire."

Watch out

✗It was raining, I stayed inside.
✓It was raining, so I stayed inside.

This is called a comma splice: joining two full sentences with only a comma, no conjunction. Add a conjunction (so, and, but) or use a period instead.

✗She said, that she was tired.
✓She said that she was tired.

English does not use a comma before 'that' introducing a reported statement.

✗I stayed home, because I was sick.
✓I stayed home because I was sick.

When 'because' introduces the main reason for something, English does not normally put a comma before it.

Real life — Proofreading an email before sending

"Can you check this sentence for me? 'I finished the report I sent it to the team.'"

"That needs something between those two parts — either a comma and 'and', or just a period."

"Right, I'll write: 'I finished the report, and I sent it to the team.'"

"Perfect — much clearer now."

Practice

Exercise 1 · Choose the sentence with correct comma use

Which sentence correctly uses commas in a list?

Exercise 2 · Choose the sentence with correct comma use

Which sentence correctly joins two full clauses with a comma and a conjunction?

Exercise 3 · Choose the sentence with correct comma use

Which sentence correctly uses a comma after an introductory phrase?

Exercise 4 · Choose the correct sentence

Which sentence does NOT need a comma before 'that'?

Exercise 5 · Choose the sentence with correct comma use

Which sentence correctly uses commas around extra (non-essential) information?

Exercise 6 · Choose the sentence with correct comma use

Which sentence correctly uses a comma before 'because'?

Exercise 7 · Identify the comma splice

Which sentence is a comma splice (an error)?

Exercise 8 · Fix the comma splice

Fix the comma splice: 'It was late, I went to bed.' (add a conjunction after the comma)

Exercise 9 · Choose the sentence with correct comma use

Which sentence correctly uses a comma with 'however' at the start?

Exercise 10 · Choose the sentence with correct comma use

Which sentence correctly uses commas to separate three adjectives before a noun?

Exercise 11 · Sort the sentences into groups

I bought bread, milk, and eggs.
After lunch, we went for a walk.
I like tea because it's warm.
She smiled, and she waved.

0 / 4 sorted

Quick challenge

Five quick questions to check what stuck.

Question 1 / 5

Score: 0/0

Which sentence correctly lists three items?

You learned

  • Use a comma to separate items in a list.
  • Use a comma before a conjunction (and, but, so) joining two full sentences.
  • Use a comma after an introductory word or phrase.
  • Use commas around extra, non-essential information.
  • Don't use a comma before 'that' or 'because' introducing essential information; don't join two sentences with only a comma (a comma splice).

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