When writing an academic paper, it is crucial to pay attention to the correct usage of commas, since they enable clarity and highlight pauses within a sentence. Since many students are unaware of the grammatical rules of setting commas, easily avoidable mistakes can happen. This article will give you a clear insight into the correct way to use a comma before “or” with helpful examples.
When to place a comma before “or”
In general, there are three cases where a comma before “or” is due. When “or” introduces an independent clause, meaning it can stand on its own, and is positioned after another sentence structure, you should place a comma. This also applies when nonrestrictive relative clauses are placed before an “or.” The third case is optional depending on the stylistic choice you make. When you list more than two objects in a series, and the last item is introduced by “or,” you can place an Oxford comma.
Comma
Introducing independent clauses
Nonrestrictive relative clauses
Series of items
No comma
Introducing dependent clauses
Short phrases
Comma rules may vary depending on different Style Guides. In general, it is to be considered whether the sentence is easily understood without using a comma. In some cases, commas can be left out to maintain clarity or to avoid ambiguity. For example, some Style Guides suggest that when two independent clauses are short and simple and have a close relation, the comma before “or” can be omitted.
Comma before “or”
There are three rules for when a comma is used before “or.” When an independent clause follows a sentence structure and is introduced by “or,” it is essential to place a comma. Additionally, when “or” follows a nonrestrictive relative clause that is always enclosed by commas, it is mandatory to place a comma. Thirdly, when you list a series of more than two objects, the conjunction “or” is often used before the last item. Depending on what stylistic choice you make, you must stay consistent with it.
Introducing independent clauses
When you are joining two clauses and the second clause is introduced by “or” and has a complete meaning on its own, a comma before “or” should be placed. There are independent clauses, meaning they contain a subject and a verb and therefore, do not need additional context to convey a complete meaning.
Examples
- When he is free, he loves reading books, or he enjoys going for a walk.
- You can study medicine, or you can study molecular sciences.
- She could drive to her parents, or she could stay at home and read a book.
Nonrestrictive relative clauses
Nonrestrictive relative clauses essentially modify a subject or an object of a sentence by adding additional information. However, this information is not crucial to the complete meaning of the sentence, which is why they are also called non-defining or non-essential relative clauses. They are typically surrounded by commas to indicate a clear separation from the whole sentence. When a sentence structure introduced by “or,” follows a nonrestrictive relative clause, the comma before has to stay.
Examples
- To read, I either go to the park, which is in front of my house, or to the library.
- She takes the dog to a friend, who lives next door, or to her mother.
- He only trusts John, who is his neighbour, or his girlfriend.
Series of items (optional)
When you are listing a series and the third object is introduced by “or,” you can place a comma before the conjunction. This only applies when you are listing more than two objects. This is the so-called Oxford Comma (or serial comma) and is a matter of style and preference. Although, it is not mandatory, when you choose to use it, you should use it consistently throughout your writing.
Examples
- Creative people should study drama, music, or art.
- The scholarship is given at Julliard, LIPA, or at FAU.
- You can try harder, change your system, or give up.
No comma before “or”
A comma is not necessary before “or,” when it introduces a dependent clause, which refers to a sentence part that cannot stand alone. Moreover, when you are linking two short phrases or two words, for example, two verbs, you do not need a comma before “or.”
Introducing dependent clauses
When a dependent clause follows another sentence structure and is introduced by the conjunction “or,” a comma should generally be left out. These types of clauses are known as dependent clauses because they fundamentally rely on additional context to convey a complete meaning.
Examples
- The subject or university that you choose is important for your career.
- I need to know whether I can pass this exam or if I have no chance.
- She had to decide between pursuing her career or following the love of her life.
Short phrases
When you are linking two short phrases, for example, two verbs or nouns with “or,” which do not contain a subject-verb-agreement and serve as a single unit, there is no need to place a comma.
Examples
- You can study or fail at this difficult test.
- He didn’t know whether he should continue or give up.
- The party of the faculty was filled with either cakes or cookies.
Test yourself!
Practice sheet
Place a comma before “or” when it is necessary in the following 10 sentences to test your understanding of the correct usage. The solutions can be found in the second tab.
- You can always go to the doctor if you are hurt or sick.
- Logical people should study maths, science or biology.
- The room always smells like candles or cookies.
- Do you want apples or peaches?
- He could go all in or give up.
- To get to the city, you can ride a bike, take the train or call a taxi.
- I can only get a coffee or a beer.
- I don’t know whether I should go out, read a book or call it a night.
- Do you like yellow flowers or green flowers?
- Would you rather go swimming or have a picnic?
- You can always go to the doctor if you are hurt or sick. (No Comma)
- Logical people should study maths, science, or biology. (Comma)
- The room always smells like candles or cookies. (No Comma)
- Do you want apples or peaches? (No Comma)
- He could go all in or give up. (No Comma)
- To get to the city you can ride a bike, take the train, or call a taxi. (Comma)
- I can only get a coffee or a beer. (No Comma)
- I don’t know whether I should go out, read a book, or call it a night. (Comma)
- Do you like yellow flowers or green flowers? (No Comma)
- Would you rather go swimming or have a picnic? (No Comma)
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FAQs
A comma before “or” is used when it introduces an independent clause that follows either a dependent or independent clause. You can also place a comma before “or” when it introduces the last item in a series of at least 3. This is called the Oxford Comma, but it is optional.
When you use either and or in a sentence, you talk about two or more options of a case. Because they coordinate the parts in a sentence by showcasing the choices one has, you don’t need to use a comma.
Example
You can either work hard or fail miserably.
Since using the Oxford comma is a matter of style and preference it is not mandatory, but you can always use it for clarity.
