Use commas to separate things in a list or series.
Correct: At the store I will buy apples, oranges, pears, and bananas.
Note: It's OK to omit the final comma before the "and" like At the store I will buy apples, oranges, pears and bananas. But never omit the final comma if it makes the sentence unclear.
- Do not place commas before or after the list or series.
Incorrect: At the store I will buy, apples, oranges, pears, and bananas, to make fruit salad tonight.
Correct: At the store I will buy apples, oranges, pears and bananas to make fruit salad tonight.
- Do not use commas when all the items in a series are linked by and, or, or nor.
Correct: Kyle and Spike and Brenda and Willow all went to the concert.
Also Correct: Kyle, Spike, Brenda, and Willow all went to the concert.
Use commas between two or more adjectives that independently modify a noun. Here's how to know whether the adjectives are functioning independently: If you could insert the word "and" between the adjectives without changing the meaning of the sentence (or producing gibberish), they are functioning independently and a comma should separate them.
Correct:People who purposefully misuse grammar are brutish, irresponsible, mean-spirited troglodytes who mangle our beautiful, versatile language.
- Some word pairs act as a single word (disc jockey, young man). Commas are not necessary with these. Note how the use of commas changes the meaning of the sentence below (both are correct, but each in its own way)She is a brilliant, young woman. She is a brilliant young woman.
Use commas before conjunctions that link independent clauses. An independent clause is part of a sentence that has its own subject and verb.
Incorrect: I'll take the blonde and you can have the redhead.
Correct: I'll take the blonde, and you can have the redhead.
Correct: I checked out three books from the library, but now I find it impossible to read them all.
Correct: Responsible pet owners do not let their animals roam free in the neighborhood, nor do they let their animals leave 'gifts' on people's yards and sidewalks.
Use a comma after introductory words, like well, yes, no, why, etc., when they begin a sentence.
Correct: Why, that's amazing!
Correct: No, I cannot come over this morning.
Use commas to offset nonessential clauses and nonessential participial phrases. A nonessential clause or phrase can be removed from the sentence without changing its meaning.
Example with nonessential clause. George Washington, our first president, served two terms.
Example with clause removed (meaning unchanged). George Washington served two terms.
The example above is correct because the meaning of the sentence is about the number of terms President Washington served. This does NOT work if you remove an essential subordinate clause. For example, if you take the sentence, "Drivers who exceed the speed limit are reckless," and remove the essential clause "who exceed the speed limit," you change the sentence to "Drivers are reckless," which changes the meaning and is also wrong! Not all drivers are reckless.
Use a comma after an introductory participial phrase.
Correct: Grasping the sword with both hands, Lancelot swung with all his might.
Correct: Holding his broken arm, John swore he would never skateboard again. Note: Don't mistake gerunds (verbal nouns with ing endings) for an introductory participial phrase.
Correct: Writing with perfect grammar is difficult but achievable. [The gerund phrase, Writing with perfect grammar is the subject of the sentence]
Also Correct: Writing with perfect grammar, I enjoyed the praise of my instructor. [The introductory phrase modifies the subject "I"]
Use a comma after an introductory prepositional phrase or adverb clause.
Correct: Halfway through the show, John and Mary started arguing in the theater.
Correct: Because your input at the group meetings is always creative and insightful, I'm putting you in charge of the project.
Use commas to offset expressions that interrupt the sentence.
Correct: Tolkien's book The Silmarillion, which I've read a dozen times, is an epic tale that covers the history of elves and men for thousands of years leading up to his Lord of the Rings. [which I've read a dozen timesinterrupts the sentence.]
- Direct address also falls into this category.
Correct:Helen, did you hear what I said?
Also Correct:That's why I'm appointing you, Thomas, leader of the group.
- Parenthetical phrases also require commas if they interrupt the sentence but do not use commas when essential.
Correct:It is, in my opinion, an excellent book.
Also correct:Are you interested in my opinion of the book? [Removing in my opinion changes the meaning of the sentence.]
Use a comma to separate dates and addresses.
Correct: This WikiHow was written Monday, May 14th, 2007.
Note: When only the month and year appear, do NOT use a comma.
Correct: I wrote this article sometime in May 2007.
Correct: Her new address is 1234 Main Street, Anytown, Maryland 12345.
Note: When the elements of the address are joined by a preposition, no commas are needed.
Correct: It is on Highway 10 near Pensacola in Florida.
Use a comma at the salutation and close of a letter.
Correct: Dear John, ... Sincerely,
- he most telltale sign someone doesn't know their comma rules is overuse. 'So when in doubt, leave it out'!
- Pay attention in school. In life, people DO judge you by your ability to write correctly.
- Out of school? Pick up a copy of 'The Little Brown Handbook' or 'Warriner's English Grammar and Composition' and actually read and do the exercises. Hint: a cheap used copy is probably just as good as a brand new one. Grammar rules rarely change.
- It's always a good idea to get a (semi-) professional to review your work. While they're not perfect, most teachers, journalists and other wordsmiths who write daily hate seeing their language butchered. Most will be happy to review your work.
- Warriner's English Grammar and Composition, which is an excellent source for grammar use, served as a reference for this WikiHow.
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