Knowing when to use a comma can drastically improve your writing and create a better experience for your readers. A comma’s function is to combine related clauses to create a complete sentence. In this article, you’ll learn how to use commas to create clear sentences.
How to Use Commas with Dependent and Independent Clauses
A clause is either dependent or independent. You can spot a dependent clause by its inability to form a complete statement on its own. Dependent clauses do not usually need commas, while independent clauses are self-contained and usually require commas.
Dependent clause: Juliet will bring the tomatoes if there are any in the garden.
Independent clauses: The restaurant confirmed that they sent my meal over an hour ago, but there is still no sign of the delivery guy.
How to Use a Comma with Coordinating Conjunctions
Coordinating conjunctions connect clauses that are equally important to the completion of a sentence. These conjunctions include and, but, or, nor, for, so, and yet. Coordinating conjunctions routinely work with commas, linking two clauses without making one more important than the other. You place the comma where the first clause ends, which is before you use the coordinating conjunction.
Example: John’s father called with the news, and John rushed to the hospital.
Example: The rain was falling, but we made it to school safely.
A few exceptions and variations to the rule:
- Avoid using a comma with coordinating conjunctions when it simply joins two words, two phrases, or when the clauses it joins are short.
Example: A nurse came in and sat on a chair.
Example: Either you stay in the house or sleep outside tonight.
How to Use Commas with Items in a Series
You should use a comma when dealing with a series of three or more words, phrases, or clauses.
Example: Sarah loves desserts her favourites are ice cream, cake, and chocolate.
Example: Each pizza can only have one topping either pepperoni, cheese, or pineapple chicken.
The comma before the coordinating conjunctions is called the serial comma. It is important to remember to include these commas in your series as they help to reduce confusion.
Confusing Example: Marcus, Winston and Shelly refurbished the house before they placed it on the market.
Correct Example: Marcus, Winston, and Shelly refurbished the house before they placed it on the market.
In the first example, the speaker could be telling Marcus that Winston and Shelly refurbished the house, or it could be the case that Marcus, Winston, and Shelly refurbished the house. However, in the second example, it is clear that three people refurbished the house.
How to Use Commas with Coordinate Adjectives
Coordinate adjectives are a group of adjectives that modify a noun (or pronoun) equally. When using coordinate adjectives, you should place a comma between each adjective that precedes the noun.
Example: The city is a wild, dark, dangerous place at night.
If a group of adjectives preceding a noun sounds unnatural with their order reversed or with and between them, then you shouldn’t use a comma between them.
How to Use a Comma with Subordinating Conjunctions
Subordinating conjunctions start clauses that tell you “when”, “where”, “why”, or “how”. They either use no punctuation or a comma. Subordinating conjunctions that relate to time and place include “when”, “whenever”, “while”, “before”, “after”, “since”, “until”, “where”, and “wherever”. Those that relate to reason and condition include “because”, “if”, “unless”, and “provided”.
Avoid Using a Comma When a Restrictive Clause Follows the Main Clause
Restrictive clauses limit the meaning of the main clause. They are known to narrow the possibilities or add essential conditions.
Example: Many of us will die if we don’t extinguish the fire.
Example: Check the doors before you leave the house.
Example: The business will fail unless there is a new investment.
Use a Comma to Indicate Any Adverbial Clause that Comes Before the Main Clause
An adverbial clause is a dependent clause that starts with subordinating conjunctions. When subordinating conjunctions join two clauses, you can reverse their order. After an introductory adverbial clause, use a comma to indicate where the main clause begins.
Example
Without comma: Vote for Patrick if you trust me.
With comma: If you trust me, vote for Patrick.
Use a Comma to Indicate a Non-Restrictive Clause.
There will be instances where the main clause shows the time, place, or condition for an action or event. In such a case, an added dependent clause may only serve to emphasize the information already given. Therefore, the original statement remains true or unchanged, and the added clause is non-restrictive.
Example: Stacy went to Canada, where she was born.
Use a Comma to Indicate an Adverbial Clause That Establishes a Contrast
The words whereas, though, and although usually require a comma and usually indicate non-restrictive material. However, instead of providing essential conditions, they create a contrast between the statements they connect. Essentially both statements are separately true.
Example: I like the dish, though the sauce is too spicy.
How to Use Commas with Conjunctive Adverbs
Conjunctive Adverbs clarify the relationship between clauses that have equal weight in a sentence or statement. Some popular conjunctive adverbs include however, also, accordingly, equally, furthermore, nevertheless, and therefore.
A conjunctive adverb is always followed by a comma; however, the punctuation that precedes it may vary. When a conjunctive adverb joins two clauses in a sentence it is preceded by a semicolon, but when it connects two sentences in a statement it is preceded by a full stop. Whether a conjunctive adverb joins two clauses or connects two sentences depends on the writer.
Semicolon Example: I love Canada; However, the Caribbean will always be my home.
Full Stop Example: I won the national championship. Therefore, I’ll be representing the country on the global stage.
How to Use Commas with Relative Clauses
Relative clauses generally add information about a specific noun (or pronoun) in the main part of the sentence. A relative clause starts with a relative pronoun: who (whose, whom), which, or that. You can either use commas or no punctuation when using relative clauses.
A Comma is not necessary to indicate restrictive relative clauses.
This is because the added information is crucial when you need to know “which one?” or “what kind” these relative clauses narrow the possibilities.
Example: People who live in glass houses should not throw stones. (Applies to specific people)
Example: Identify the woman whose picture is on the wall. (Applies to a specific person)
It is important to be aware of commas used accidentally with a restrictive clause.
Incorrect Example: Doctors, who create fraudulent medication, should go to jail.
Correct Example: Doctors who create fraudulent medication should go to jail. (Not all doctors, only those who create fraudulent medication)
Use commas to indicate non-restrictive relative clauses.
Relative clauses are non-restrictive if you already know “which one” or “what kind.” Therefore, this nonessential information answers the question “what else about it?”
Example: Sharks differ from whales, which surface to breathe. (Applies to all whales)
Example: He parks his car on Main Street, which leads to the Chapel. (You already know which street)
You use two commas when a non-restrictive clause interrupts the main clause.
Examples: Computers, which perform exceptional tasks, are resilient.
Inaccurate Use of Commas
Commas are often misplaced in different sentence structures. The following is a list of common errors you should learn to avoid:
- Putting a comma between a subject and a verb
Incorrect Example: the hand of the clock, spun uncontrollably.
Correction: the hand of the clock spun uncontrollably.
- Putting a comma before an ordinary prepositional phrase (prepositional phrases serve the same function as either adjectives or verbs)
Incorrect Example: She had first driven a car, in St James in 1991.
Correction: She had first driven a car in St James in 1991.
- Putting a comma before a noun clause
Incorrect Example: She already knows, what is going to happen at the ball tomorrow.
Correction: She already knows what is going to happen at the ball tomorrow.
- Putting commas with coordinating conjunctions joining words or phrases
Incorrect Example: The protest reached Cuba, and other Caribbean Islands.
Correction: The protest reached Cuba and other Caribbean Islands.
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