Mary ate dinner.
Comma Used With "and" or "but" to Join Two Complete Sentences Together
Example1: Mary ate dinner, and she ate dessert.
Example 2: Mary ate dinner, but she didn't eat dessert.
*No comma if second word group is not a complete sentence:
Mary ate dinner and also ate dessert. (subject missing in second group).
Comma Used After Introductory Word Group Before the Main Sentence
Because she had no money, Mary ate dinner at home.
Comma Used Between All Items In a List of Three or More Items
Mary's dinner consisted of salad, soup, chicken, and toast.
Comma Used to Show Nonrestrictive Word Groups That Only Add Information
Nonrestrictive: Mary ate the dinner, which was prepared Cajun style.
Restrictive: Mary ate the dinner that Ivan made.
Note: The words "that Ivan made" are "restrictive" because they restrict the dinner to the specific one Mary ate. The dinner is not the dinner made by Fred or Joyce but the dinner made by Ivan.
Nonrestrictive Example 2: Mary's dinner, which included several food groups, gave her heartburn.
In this case, the words "which included several food groups" do not restrict our knowledge to a specific dinner. Therefore, the words are nonrestrictive and should be set off by commas.
Nonrestrictive Example 3: Mary's dinner, with its wide range of flavor, was digested slowly.
If removed, the words "with its wide range of flavor" would not significantly alter the sentence's meaning because they are just additional information and do not limit the word "dinner."
Comma Used with Words Like "however" and Phrases Like "for example"
Example 1: Mary ate dinner; however, she was hungry an hour later.
Example 2: Mary's dinner was made with several spices; for example, the chicken was sprinkled with Cayenne pepper.
*Note: The semi-colon may be used to connect two complete sentences together, which is the case in both of these examples. See the first rule under semi-colon rules below.
Comma Used with Word Groups that Contradict
Example 1: Mary ate dinner, not breakfast, every day.
Example 2: Unlike Ivan, Mary ate dinner every day.
Comma Used for Additional Information
Example 1: Mary, as far as Ivan knows, ate dinner.
Example 2: Mary ate dinner at 9:00, give or take a few minutes.
Comma Used with Descriptive Word Groups
Example 1: Her dinner at last eaten, Mary belched. Blue words modify Mary.
Mary belched, her dinner at last eaten. Blue words modify belched
Mary, her dinner at last eaten, belched. Blue words modify Mary.
Example 2: Mary startled Ivan, her belch having sounded like a gunshot. Blue words modify Mary.
Her belch having sounded like a gunshot, Mary startled Ivan. Blue words modify Mary.
Mary, her belch having sounded like a gunshot, startled Ivan. Blue words modify Mary.
Comma Used to Set Off the Following: Names of People Directly Addressed by the Sentence; the Words "yes" and "no"; Interrogative (Question) Tags; and Mild Interjections
Person Directly Addressed by the Sentence: Ivan, Please Pardon Mary for belching at dinner.
"Yes" or "No": Yes, Mary's belch disturbed Ivan's tranquility.
Interrogative (Question) Tags: Mary's dinner did exceed the 1,000 calorie limit, didn't it ?
Mild Interjection: Well, Mary ate dinner again.
Comma Used with Words Such as "she said" to Indicate Direct Quotations
Example 1: Ivan said, "Mary ate dinner at 9:12."
Example 2: "Ivan made my dinner," announced Mary.
Commas Used with Numbers, Dates, Titles, and Addresses
Numbers (Use Comma if Number is Longer than Four Digits. If Comma is Four Digits Exactly, Comma use is Optional): Mary ate 50,000 green peas last year.
Dates: On September 14, 1993, Mary ate dinner.
Titles (Such as Ph.D., D.D.S., etc.): Mary Chambers, M.D., ate dinner.
Addresses Example 1: Mary ate dinner at her house on 250 Bolus Way, Digest, Georgia 31072.
Addresses Example 2: Mary ate dinner in Digest, Georgia, in 1993.
*Note: Do not use zip code abbreviations for states. GA would be incorrect for Georgia in the sentence above.
Comma Used to Avoid Confusion
To eat is normal; to gorge oneself, gluttony.