The Comma in Punctuation

A comma is a  punctuation mark  that separates elements and ideas within a sentence. The comma is the most common mark of punctuation—and the most commonly misused. In his  Time magazine essay,  In Praise of the Humble Comma, author and essayist Pico Iyer compared the  punctuation mark to a flashing yellow light that asks us only to slow down. Knowing when to insert that flashing light (the comma)  and when it is better to let the sentence ride on without interruption is a conundrum that challenges even the most expert of writers. Learning a few simple rules can help you master when to use a comma and when to omit it. How to Use Commas Correctly Place a comma in front of any coordinating conjunction (and, but, for, nor, or, so, and yet) that joins two independent clauses  in a compound sentence. Author  Maya Angelou  used this example of a comma before a coordinating conjunction: I sliced onions, and Bailey opened two or even three cans of sardines and allowed their juice of oil and fishing boats to ooze down and around the sides. (Maya Angelou, I Know Why the Caged Bird Sings) Note how Angelous sentence contains two independent clauses—each could stand on its own as a sentence—but the author, instead, decided to join them with the coordinating conjunction  and, which was preceded with a comma. If the two independent clauses are short, however, you can usually omit the comma: Jimmy rode his bike and Jill walked. In most cases, do  not  use a comma before a conjunction that links two words or phrases: Jack  and  Diane sang  and  danced all night. In a Series Use commas to separate words and phrases in a series of three or more: Everyone hollered, hooted, back-slapped, and jumped into the air. (Keith  Nolan,  Into Cambodia) Use a  comma to separate  adjectives  that are  coordinate  (adjectives that are interchangeable before or after a  noun): The books are  trim, crisp, clean,  especially in the moment when they arrive from the printer in a cardboard box. (John  Updike,  Self-Consciousness) You can tell whether adjectives are coordinate by inserting the conjunction  and  between them. If the sentence makes sense, the adjectives are coordinate and should be separated by commas. By contrast,  cumulative adjectives—two or more  adjectives  that build on one another and together  modify  a  noun—are generally  not  separated by  commas: I  wrote in a marble-floored room at the back of the little lavender house we rented on Essex Road. (John  Updike,  Self-Consciousness) After an Introductory Clause To signal a pause, use a comma after an introductory word, phrase, or clause: For  the first few days of his life, Wilbur was allowed to live in a box near the stove in the kitchen. (E.B. White, Charlottes Web)   Use a comma after a  phrase  or  clause  that precedes the  subject  of the sentence: Lacking brothers and sisters, I was shy and clumsy in the give and take and push and pull of human interchange. (John  Updike,  Self-Consciousness) If the introductory element doesnt require a pause, you can usually omit the comma. To Set Off Phrases Use commas to set off  interrupting phrases  and  nonrestrictive elements—words, phrases, or clauses that provide  added (though not essential) information to a sentence. For example: He sat back in his chair, slightly ashamed of himself, and laid down his pen. (George Orwell, Nineteen Eighty-Four)   But dont use commas to set off words that directly affect the essential meaning of the sentence: Your manuscript is both good and original. But the part that is good is not original, and the part that is original is not good. (Samuel Johnson) Other Uses for Commas Use a comma between the day and year in a date, in numbers greater than 999 (except in street addresses and years), and between the city and state in a location: The last time I was there was Jan. 8, 2008.The house is located at 1255 Oak Street, Huntsville, Ala.He had 1,244,555 marbles in his collection.In the year 1492, Columbus sailed the ocean blue. When a phrase refers to a month, day, and year, set off the year with a comma, says The Associated Press Stylebook, 2018: Feb. 14, 2020, is the target date The Oxford, or Serial, Comma The  Oxford  comma, also called the serial comma, precedes the  conjunction  before the final item in a list of three or more items. It is usually optional and is generally  not  used when only  two  parallel  items are connected by a conjunction:  faith and charity: This song was composed by Moe, Larry, and  Curly. Though the  AP Stylebook  is a notable exception, most American  style guides  recommend using the serial comma for the sake of  clarity  and consistency. In contrast, most British style guides discourage use of the serial comma unless the items in the series would be confusing without it. As Joan I. Miller says in The Punctuation Handbook: Nothing is gained by omitting the final comma in a  list, while clarity can be lost in some cases through misreading. The Oxford comma is so called because it has traditionally been used by editors and printers at Oxford University Press. New Englanders may favor the term  Harvard comma  (the convention is also followed by Harvard University Press). Commas and Meaning The comma can alter the  meaning of a sentence, says  Noah Lukeman in A Dash of Style: The Art and Mastery of Punctuation: The windows with the glass treatment are holding up well.The windows, with the glass treatment, are holding up well. In the latter sentence, the windows are holding up well because of the glass treatment, says Lukeman. In the former, the windows, which were treated with a glass treatment, are holding up well in general. The entire meaning of the sentence changes, simply due to the comma placement, he notes. Source Miller, Joan I. The Punctuation Handbook. Paperback, Wipf Stock Pub, 1683.