1.  Use a comma before a coordinating conjunction linking independent clauses

                    Independent clause, coordinating conjunction independent clause:
                                The sky was dark, and the air was still.
                               The rain was pouring, and the wind was blowing

                                Coordinating Conjunctions: and, but, for, or, nor, so, yet

2.  Use Commas after an introductory clause, phrase or word

                   A. Introductory clause:
                                When it comes to eating, you can sometimes help yourself more by
                                            helping yourself less.

                    B. Introductory Phrase:
                                Beginning in infancy, we develop lifelong tastes for sweet and salty foods.

                    C. Introductory Word:
                                Nevertheless, all sugars are metabolized into blood sugar.

3.  Commas to separate items in a series

                    A. Word, word, and word:
                                Marriage requires respect, compassion, and discipline.

                   B. Phrase, phrase, and phrase:
                                For recreation, I spent my afternoons reading romance novels, playing
                                            Chinese checkers, and writing in my diary.

                    C. Clause, clause, and clause:
                                We have learned that commas have several uses, that they are
                                            important grammatical tools, and that our understanding of
                                            them can be perfected with practice.

4.  Use commas to separate coordinate adjectives

        Coordinate adjectives are two or more adjectives that equally modify a noun. Separate
                coordinate adjectives with commas (unless the coordinate adjectives are joined by a
                coordinating conjunction such as and or but). Comma Cautions: (1) Do not put a
                comma after a final coordinate adjective and the noun it modifies. (2) Do not put a
                comma between adjectives that are not coordinate.
 

                Coordinate Adjectives:
                         The large, restless crowd waited for the concert to begin. (Both adjectives
                           modify the noun crowd)

                                        The audience cheered happily when the pulsating, rhythmic music
                                                    filled the stadium. (Both adjectives modify the noun music)
 

                Noncoordinate Adjectives:

                                        The concert featured several new bands.
                                       Each had a distinctive musical style.

        If you are not sure whether you are dealing with coordinate or noncoordinate adjectives,
        try this exercise: Reverse the adjectives and see if they still make sense. If not, then they
        are not coordinate adjectives and do not need commas (The sentence The concert featured
        new several bands would not make sense).

5.  Use commas to set off nonrestrictive (nonessential) elements

        Restrictive elements (also called essential elements) and nonrestrictive elements (also
        called nonessential elements) function as modifiers in sentences. A modifier is a word or
        group of words that describes or limits other words, phrases, and clauses. Nonrestrictive
        (nonessential) elements are set off by commas.

                   A.   Nonrestrictive element, independent clause:
                                An energetic man, John enjoys cooking.

                   B.   Beginning of independent clause, nonrestrictive element, end of independent
                                        clause:
                               John Jones, who raises his own vegetables, enjoys cooking.

                   C.  Independent clause, nonrestrictive element:
                                John Jones enjoys cooking, which his family appreciates.

6.  Commas to set off parenthetical and transitional expressions, contrasts, words of direct
                    address, and tag questions

                    Words, phrases, or clauses that interrupt a sentence but do not change its essential
                                meaning should be set off , usually with commas.

                   Conjunctive Adverbs: modify by creating logical connections in meaning; words
                                such as however, also, furthermore, therefore, etc:

                                The American Midwest, therefore, is the world's breadbasket.
                               California and Florida are important food producers, for example.

                   Parenthetical Expressions: "asides," additions to sentences that the writer thinks
                                of as extra:

                                American farmers, according to U. S. government figures, export more
                                            wheat than they sell at home.
                               A major drought, sad to say, reduces wheat crops drastically.

                   Expressions of Contrast: describe something by stating what it is not and setting
                                it off by commas:

                                Feeding the world's population is a serious problem, but not an
                                            intractable one.
                               We must work against world hunger continuously, not just when
                                            emergencies develop.

                    Words of Direct Address: indicate the person or group spoken to and are set off
                                by commas:

                                Join me, brothers and sisters, to end hunger.
                               Your contribution, Steve, will help us greatly.

                   Tag Questions: consist of a helping verb, a pronoun, and often the word not,
                                generally contracted:

                                Worldwide response to the Ethiopian famine was impressive, wasn't it?

7.  Commas With Quoted Words

        Use a comma to set off quoted words from short explanations in the same sentence. This
        rule holds whether the explanatory words come before, between, or after the quoted words.

                   Speaking of ideal love, the poet William Blake wrote, "love seeketh not itself to
                                please."
                   "My love is a fever," said William Shakespeare about love's passion.
                   "I love no love," proclaimed poet Mary Coleridge, "but thee."

        When quoted words end with a question mark or an exclamation point, keep that
        punctuation even if explanatory words follow:

                    "O Romeo! O Romeo!" called Juliet as she stood at her window.
                   "Wherefore art thou Romeo?" continued Juliet as she yearned for her
                                new-found love.

8.  Commas in names, dates, and addresses

        When you write dates, names, and numbers, be sure to use commas according to accepted
        practice.

                    Commas with dates:
                                Between the date and the year:  July 20, 1969.
                               Between the day and the date: Sunday, July 20, 1969.

        Within a sentence, after the day and year in a full date: Everyone wanted to be near a
        television set on July 20, 1969, to watch Armstrong emerge from the lunar landing module.

         Do not use commas in the following instances:
               When a date contains the month with only a day: It rained heavily on July 21.
               When a date contains the moth with only a year: It was July 1969.
               When using an inverted date: 20July 1969.

        Commas with names, places and addresses:
               When an abbreviated title comes after a person's name: Rosa Gonzales, M.D.
               When you invert a name: Troyka, David.

        Between a city and state: Lawton, Oklahoma.

        Commas with letters:
               After the letter's opening: Dear Betty,
               After the letter's closing: Sincerely, John or Best regards, John

9.  Commas to Clarify Meaning

        Sometimes you will need to use a comma to clarify the meaning of a sentence, even though
        no other rule calls for one:

               NO: Of the gymnastic team's twenty five were injured.
               YES: Of the gymnastic team's twenty, five were injured.

                NO: Those who can practice many hours a day.
               YES: Those who can, practice many hours a day.

               NO: George dressed and performed for the sellout crowd.
               YES: George dressed, and performed for the sellout crowd.