Writers use punctuation marks to help readers follow ideas and understand where thoughts should be connected or separated.
He was nervous—first day on the job—and along had come this fascinating girl, standing in the checkout line with the unfocused stare one often sees in young children, her face turned enough away that he might take several full looks at her as he packed sturdy bags full of food and the goods of modern life.
—from "Checkouts" written by short story writer Cynthia Rylant
The sentence has used dashes and commas to link and separate ideas about two characters.
Use a period (.) to end a declarative sentence, a mild imperative sentence, and an indirect question.
Declarative Sentence – The stone is large and smooth.
Imperative Sentence – Open the window about six inches.
Indirect Question – I asked him what he wanted.
Use a question mark (?) to end an interrogative sentence, an incomplete question, or a statement intended as a question.
Direct Question – Which mountain are you planning to climb?
Incomplete Question – I heard the bill was high. How much?
Statement as Question – They have twelve pets?
Use an exclamation mark (!) to end an exclamatory sentence, an urgent imperative sentence, and most interjections.
Exclamatory Sentence – What a remarkable person she is!
Urgent Imperative Sentence – Don't let go of the wheel!
Interjection – Good grief! I think she's going to win the race.
Commas With Compound Sentences
Use a comma before the coordinating conjunction in a compound sentence. Make sure there is an independent clause on each side of the comma and conjunction.
Jose wanted to attend the game, but he decided to do his report instead.
We must win tonight or face embarrassment tomorrow. (no comma needed)
Commas Between Items in a Series
Use commas to separate three or more words, phrases, or clauses in a series. Include a comma before the coordinating conjunction.
Ellen bought new jeans, a plaid skirt, and a pair of gloves.
They drove to the post office, parked the car, and unloaded the boxes.
Commas Between Adjectives
Use commas to separate adjectives of equal rank. (Do not use commas to separate adjectives that must stay in a specific order.)
A narrow, rough road led to the country market.
Many new sports books are available in the library. (no commas needed)
Commas After Introductory Material
Use a comma after an introductory word, phrase, or clause.
Introductory Word – No, I don't think I can go.
Introductory Phrase – Reaching the lake, she searched for her canoe.
Introductory Clause – When she entered the building, she was confused and frightened.
Commas with Parenthetical Expressions
Use commas to set off parenthetical expressions.
Names of People Being Addressed – I know, Susan, that you will do well.
Certain Adverbs – I decided, therefore, to wait.
Common Expressions – Mr. Wong, I believe, agreed to go.
Contrasting Expressions – The room is narrow, not wide.
Commas With Nonessential Expressions
A nonessential expression, short or long, gives additional information about someone or something in a sentence. Because it can be left out without changing the basic meaning of the sentence, it is set off with commas. If the information is essential, don't use commas.
Essential – My cousin the computer expert is growing rich. (which cousin?)
Nonessential – Cathy, a computer expert, knows BASIC and COBOL.
Essential – The man standing in the corridor is the principal. (which man?)
Nonessential – Dr. Rogers, now standing in the corridor, is the principal.
Essential – The boy who lives next door plays the French horn. (which boy?)
Nonessential – My cousin Phil, who lives next door, plays the French horn.
Other Use of Commas
Look at the examples below to learn more uses for commas:
Parts of a Place Name – Houston, Texas, is a rapidly growing city.
Parts of a Date – On September 19, 1939, German panzers invaded Poland.
Name With Title – Jim Thon, M.D., discussed safe ways to lose weight.
Mailing Address – Send the package to Jeremiah Brown, 10 Elk Lane, Glen Cove, New York 11542.
Salutation and Closing – Dear Peter, Very truly yours,
Numbers – 31,654 envelopes (but no comma in a four-digit year 1949)
Elliptical Sentence – Lorraine plays the guitar; her brother Sam, the flute.
Direct Quotation – "In a few minutes," laughed Julio, "you'll know the surprise."
To Prevent Confusion – For Carla, Jonas had designed a unique costume.
Use a semicolon to join independent clauses not already joined by a comma and a coordinating conjunction.
Alan reached the mouth of the cave first; he peered inside and decided to wait for his friends.
You can also use a semicolon to join two independent clauses joined by a conjunctive adverb or a transitional expression. Use a comma to set off the conjunctive adverb or transitional expression.
Karen wants a new car; however, she will wait until she has saved $2,000 for a down payment.
My sister is an outstanding student; as a result, she won a four-year college scholarship.
Semicolons to Avoid Confusion
Use a semicolon to avoid confusion when items in a series already contain commas.
I sent notes to Mr. Neilsen, my science teacher; Mrs. Jensen, my history instructor; and Mrs. Seltz, the librarian.
Colons as Introductory Devices
Use a colon before a list of items following an independent clause. Don't use a colon if the list just finishes an independent clause.
Use Colon – Grandfather grew a variety of vegetables: tomatoes, peas, lettuce, and corn.
No Colon – Grandfather's garden features tomatoes, peas, lettuce, and corn.
Use a colon to introduce a quotation that is formal or lengthy or a quotation that does not contain a "he said/she said" expression.
The judge nodded slowly: "Case Dismissed."
Use a colon to introduce a sentence that summarizes or explains the sentence before it.
The speaker repeated her main point: Leash laws protect dogs as well as people.
Use a colon to introduce a formal appositive.
She showed slides of the most isolated spot on Earth: Antarctica.
Other Uses of Colons
Numerals Giving Time – 9:10 A.M., 10:15 P.M.
References to Periodicals – Cornell Law Review XIV: 76 (volume: page)
Biblical References – Ecclesiastes 1:5 (chapter: verse)
Subtitles for Books and Magazines – Emotion: Learning to Control Feelings
Salutations in Business Letters – Dear Ms. Green:, Gentlemen:
Labels Used to Signal Important Ideas – Warning: For external use only.
