Comma Before “Or” | When to Use a Comma Before Or

When do we use a comma before or? Confusion usually surrounds comma usage. Coordinating conjunctions usually play a role in this perplexing area. The word “or” is no exception.

Sometimes a comma precedes “or” and sometimes it does not. Deciphering when to employ a comma helps improve the clarity of your writing. To break this conjunction “code” you need to understand the difference between independent and dependent clauses.

When to Use a Comma Before Or

Independent vs Dependent Clauses

Simply put an independent clause represents a finished thought. It operates as a simple sentence with a subject and a verb. In a complex sentence, an independent clause works in tangent with another clause: dependent or independent.

In contrast, a dependent clause cannot function as a simple sentence. It labors as a modifier for an independent clause. In essence, a dependent clause is a word group that provides extra detail in a sentence.

Coordinating conjunctions and “or”:

“Or” is one of seven coordinating conjunctions that join two clauses. You can easily memorize these seven coordinating conjunctions with the mnemonic FANBOYS. Each letter stands for one of these words: “for”, “and”, “nor”, “but”, “or”, “yet” and “so” .

You use a comma when any of the coordinating conjunctions precede an independent clause. In contrast, you do not need a comma before the conjunction to join a dependent clause.

Each coordinating conjunction serves a purpose. “Or” introduces choice into a sentence. It combines two grammatical elements of equivalent weight.

Independent Clauses Need a Comma Before Or

Strong concise statements develop when you place a comma before “or”. Using a comma to join two independent clauses makes a sentence easier to read.

  • Mary may choose to buy a dog, or she may choose to purchase a lama.

You can reduce both clauses to simple sentences by removing the coordinating conjunction “or”. Try separating the clauses to see if they express a complete thought.

  • Mary may choose to buy a dog.
  • She may choose to purchase a lama.

If the coordinating conjunction joins two simple sentences a comma must precede it.

No Comma Before a Dependent Clause

Conjunction connecting a dependent clause requires no punctuation.

  • Mary may choose to buy a dog or a lama.

Without a subject and a verb, the second clause cannot stand alone as a simple sentence. Hence, the second clause follows the conjunction and becomes dependent on the first clause.

Comma Before “Or” In A List

In a list with two items never add a comma before or. The second item in the list will operate as a dependent clause. If “or” treads on the heels of a dependent clause no comma heralds the conjunction.

  • Would you like water or milk?

In this example, water coordinates with milk. This coordination makes the comma unnecessary.

When a list consists of three or more items you have a choice to make. You may add a comma before “or” or not. The serial comma is a hotly debated topic.

The serial comma often goes by another name: the Oxford comma. The comma gets its name from the Oxford University Press that regularly employs its use. Fans of the serial comma argue that a comma before “or” makes a sentence easier to read. This is true in a sentence with plenty of coordinating items.

  • Do you want a red, white, or black crayon?
  • Do you want a red, white or black crayon?

Both examples above are correct. Some writers use the serial comma while others do not. This coma is a stylistic choice.

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When to Use a Comma Before Or

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Last Updated on October 22, 2023

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