The comma is one of the most commonly used punctuation marks in English. Unfortunately, commas are often used incorrectly. Here are the rules for using commas with explanations, exceptions to the rules and examples. Once you have finished studying these rules, test your understanding with the comma use quiz.
1. Use Commas in Lists
Use commas to separate elements in a list of three or more items. Items in a list may bay nouns:
He received a bicycle, a new computer, a board game, and a watch for his birthday.
Jennifer ate a hamburger, potato chips, and some ice cream for lunch.
Items in a list can also be verb forms:
I enjoy hiking, playing golf, and reading in my free time.
Peter bought the ticket, had a quick lunch, and boarded the plane for Denver.
Note: Difference between British and American English
British English generally does not place a comma before the final 'and' in a list. American English, on the other hand, also places the comma before the final 'and'.
UK: I bought some soap, towels and a tooth brush.
USA: I bought some soap, towels, and a tooth brush.
2. Use Commas to Separate Adjectives
Commas are used to separate adjectives that are similar in nature which are placed directly before the noun they modify.
Peter enjoys intricate, complicated journeys.
She spent money on expensive, wasteful, unimaginative clothes.
If the adjectives describe different aspects of the noun, no commas is used.
Peter bought a fast new red corvette last week.
Jane is looking for a used round metallic object.
Note: Remember that adjective order is important when using more than one adjective to modify a noun.
3. Use Commas with Subordinate Clauses Which Begin Sentences
Subordinate clauses are also known as dependent clauses. In other words, they must be used with independent clauses because they can not stand on their own. For example, these two subordinate clauses are not complete without another, independent clause to complete the sentence.
If he comes
Although it was difficult
Subordinate clauses can be placed at the end of sentences, or at the beginning of sentences. When placing subordinate clauses at the beginning of sentences, use a comma.
Although he was late, we had a good time.
We had a good time although he was late.
She usually stays for lunch when she comes to visit.
When she comes to visit, she usually stays for lunch.
4. Use Commas with Coordinating Conjunctions
Coordinating conjunctions are often referred to as FANBOYS (for, and, nor, but, or, yet, so). Coordinating conjunctions connect two simple sentences to make a compound sentence.
I worked hard on the project yesterday, but I haven't finished it yet.
She stayed out until midnight, and she got up early for work the next day.
5. Use Commas with Introductory Comments
Words that introduce sentences such as linking words, sequencing words or other connective adverbs (consequently, however, moreover, etc.) are followed by a comma in English.
However, we decided to wait on the investment until next quarter.
Finally, let's take a look at what this all means for the future.
6. Use Commas to Introduce Direct Speech
Direct speech uses quotes ("") to directly repeat what someone else has said. Use a comma before direct speech.
Peter said, "I'm not coming with you this time."
Angie stated flatly, "I hate this job!"
Note: If direct speech begins a sentence, use a comma rather than a period within the quote.
"This is really difficult," said the student.
"It's time we take a vacation," declared Fred.
Note: Do not use a comma in indirect or reported speech. Reported speech is used to report rather than directly state what someone has said.
Mary told me she wanted to join a club.
The teacher said we had to prepare for a test the following week.
7. Use Commas with Unusual Word Order
Modifying words and expressions are generally placed in a specific position in a sentence. For example, adverbs of frequency are usually placed before the main verb. Sometimes, words or expressions are placed differently to stress a point. In this case, use two commas to offset this word or expression.
Peter, consequently, decided to stay another week.
The department, hesitant with distrust, refused to consider the idea.
8. Use Commas with Non-Defining Relative Clauses
Relative clauses can be broken into two types: Defining and non-defining relative clauses. Defining relative clauses provided essential information, non-defining relative clauses provide information which is additional, but not essential, to understanding. Use commas to offset non-defining relative clauses.
Pete, who was the team captain, came up to bat first.
My house in London, which was built in 1784, is close to all the great attractions.
9. Use Commas with Numbers
Commas are used to separate each group of three numbers for larger numbers.
10. Use Commas with Written Dates
Commas separate dates that are written out by placing a comma after the day.
March 10, 1978
August 21, 1997