The Comma in Punctuation

Commas are punctuation used to divide clauses and ideas inside sentences. The comma is the most widely and often misused punctuation mark.

Author and writer Pico Iyer likened the punctuation mark to “a blinking yellow light that urges us just to slow down” in his Time magazine piece titled “In Praise of the Humble Comma.” Even the most experienced writers find it challenging to know when to use that flashing light (the comma) and when it is preferable to let the phrase continue uninterrupted. Learning some basic guidelines lets you grasp when to use and when to omit a comma.

How to Use Commas Correctly

Any coordinating conjunction (and, but, for, nor, or, so, and yet) that connects two independent clauses in a compound sentence should be proceeded by a comma. Maya Angelou, a writer, offered the following illustration of a comma before coordinating conjunction:

  • “I cut onions while Bailey opened two or three sardine cans, letting the oily fluid drip down the sides and over the edges.” I Know Why the Caged Bird Sings by Maya Angelou

Remember that Angelou’s statement consists of two distinct clauses, either of which may function as a complete sentence. However, the author chose to link them with the coordinating conjunction, followed by a comma. On the other hand, if the two separate phrases are brief, you may often eliminate the comma:

Jill walked as Jimmy rode his bike.

Generally speaking, a comma should not be used before a conjunction that joins two words or phrases:

All night long, Jack and Diane sang and danced.

In a Series

When there are three or more words or sentences in a row, use commas to divide them:

Everyone shouted and cheered, gave each other backslaps, and sprang into the air. (Into Cambodia, Keith Nolan)

A comma should be used to separate coordinate adjectives (adjectives that may be used either before or after a noun):

  • “The books are trim, sharp, and clean, particularly when they first leave the printer in a cardboard box.” (From Self-Consciousness by John Updike)

You can determine if they are coordinated by using the conjunction between two adjectives. Commas should separate the adjectives if the phrase makes sense and they are coordinated. Contrarily, commas are often not used to divide cumulative adjectives, which are two or more adjectives that build upon one another and alter a noun collectively:

  • “I wrote at the rear of the tiny lavender home we leased on Essex Road, in a room with a marble floor.” (From Self-Consciousness by John Updike)

After an Introductory Clause

After an initial word, phrase, or sentence, a comma should be used to indicate a pause:

  • “Wilbur was permitted to reside in a box near the stove in the kitchen for the first few days of his existence.” (From Charlotte’s Web by E.B. White)

“Lacking brothers and sisters, I was bashful and ungainly in the give and took and pushed and pulled of human exchange.” Use a comma after the phrase or clause before the sentence’s subject. (From Self-Consciousness by John Updike)

You may skip the comma if there isn’t a need to pause after the opening part.

To Set Off Phrases

Interrupting clauses and non- restrictive elements—words, phrases, and clauses that give more (but not necessary) information to a sentence—should be set off by commas. For instance:

He put his pen down and slumped back in his chair, feeling embarrassed. (From Nineteen Eighty-Four by George Orwell)

However, avoid using commas to separate words that significantly alter the sense of the statement. For example:

  • “Your manuscript is both nice and unique. However, the good portion is not original, and the original part is not excellent.” Muhammad Johnson

Other Uses of Commas

Use a comma between the day and year in a date, between the city and state in a location, and between numerals higher than 999 (except years and street addresses):

  • I last visited that location on January 8, 2008.
  • The residence may be found at 1255 Oak Street in Huntsville, Alabama.
  • His collection of marbles totals 1,244,555.
  • Columbus sailed the ocean blue in the year 1492.

The AP Stylebook, 2018 advises using a comma to separate the year when a statement relates to a month, day, and year:

  • February 14, 2020, is the deadline.

The Oxford, or Serial, Comma

In a list of three or more items, the conjunction comes before the Oxford comma, sometimes known as the serial comma. When just two parallel components are joined by a conjunction, such as faith and charity, it is frequently optional and often not utilized.

Moe, Larry, and Curly wrote the lyrics to this song.

The serial comma is advised by most American style manuals for uniformity and clarity, except the AP Stylebook. In contrast, most British style manuals advise only using a serial comma if doing so would clarify the items in the series. Nothing is gained by skipping the last comma in a list, whereas clarity may sometimes be lost due to misinterpretation, according to Joan I. Miller in The Punctuation Handbook.

The Oxford comma got its name because Oxford University Press editors and printers have long utilized it. Some New England people prefer the “Harvard comma” (Harvard University Press also follows the convention).

Commas and Meaning

According to Noah Lukeman in A Dash of Style: The Art and Mastery of Punctuation, the comma may change the meaning of a sentence:

The windows with the glass treatment are holding up well.

The windows, with the glass treatment, are holding up well.

According to Lukeman, the glass treatment in the last sentence is why the windows hold up well. The windows of the former, which had a glass coating, are enduring well overall. He observes that the location of the comma “changes the whole meaning of the statement.”

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