Word usage and punctuation are more likely to trip writers than basic grammar. Of particular danger in punctuation are commas, apostrophes, semicolons, colons, and hyphens. This introduction to punctuation discusses the uses of punctuation marks, not formatting issues. For information about typing and punctuation, see our documents on formatting.
Sentences end with periods. The common error is to replace a period with a “weaker” form of punctuation, such as a comma or semicolon. Writers must rely on experience to make the proper determination in some cases. The rule of using a period at a “full stop” is insufficient; make sure periods end complete sentences, not fragments.
Commas represent short pauses in speech. Keeping this in mind might help a writer avoid the overuse of commas. Many readers and writers insert commas too often. Commas do not precede conjunctions unless indicative of a list. Removing commas when possible makes for stronger, easier-to-read passages of text.
The most common use for commas is the construction of lists. If the list is “simple” there is no need for a comma before the conjunction according to most current grammar texts. However, we prefer a comma be used before the conjunction in all cases. Strunk & White suggest commas in all lists, but the AP Stylebook does not. If any item in the list includes a conjunction, replace the commas with semicolons.
Addressing a Person
When addressing a person, use a comma after his or her name. When a direct address is implied, but a specific name not used, use a comma.
Example: Shelly, would you please hand me the pen?
Example: No, sir, I did not remember to bring paper to class.
A comma follows the day of the month in a long date. Some experts suggest a comma should also follow the year.
Phrases and Clauses
When a phrase or clause is nonessential to the structure of a sentence, use a comma to mark the phrase or clause. Comments meant to give background are known as appositives.
Example: The cat, confused by living with dogs, learned to beg and shake hands on command.
Adjectives of equal importance are separated by commas.
Example: The cold, silent breeze moved across the barren land.
Use a comma before a conjunction when two thoughts are expressed. Do not use a comma when there is one thought.
Example: She was glad she wrote the novel, but she hated the publicity.
Quotes (“ ”)
Introduce or end a quotation with a comma, separating it from the remainder of the sentence. The comma goes within the quotation marks.
Question Mark (?)
Question marks end interrogatives, better known as questions.
Exclamation Point (!)
Exclamation points end sudden statements, interjections, and sentences expressing strong emotions. Use exclamation points sparingly; overuse reduces their effectiveness. In works of fiction it is advisable to reserve exclamation points for dialogue.
Quotation Marks (“ ”)
Use quotation marks to indicate dialogue; to define or clarify ideas; and to emphasize words or phrases in special cases.
Example: “Hello,” the clerk said. “Can I help you?”
Example: When something is “fly,” it is “very cool.”
Example: There is nothing worse than being made “redundant” during a merger.
Unfortunately, possessives are not as simple as thought. For most nouns, add an apostrophe and an “s” to indicate ownership. Experts disagree on the status of nouns ending in “s” — some suggest adding the apostrophe and “s” improves clarity, while others argue adding the “s” is only proper if it is spoken. Still other authorities claim the “s” is never added, except in Biblical names! We tend to follow the “if spoken” rule. For possessive proper nouns ending in “s,” do not add the additional “s” after the apostrophe.
Yes, this can be quite confusing. Keep a copy of Strunk & White nearby, along with applicable style guides.
Use contractions with care. While contractions make dialogue more believable, they also decrease the readability of exposition. The words commonly contracted are will, has, and was linked to not.
A common error is the use of an apostrophe following a year and the letter “s.” It is improper to write, “During the 1970’s, he was in Europe.” There should be no apostrophe in the preceding example. However, do use an apostrophe in place of the century when referring to a decade. It is proper to write, “During the '70s, he was in Europe.”
Semicolons represent pauses longer than those of commas. Semicolons combine two closely-related independent clauses or replace commas in lists.
Semicolons combine short sentences with relating subjects or predicates. In these instances the semicolon acts as a conjunction.
Example: John writes a magazine column; the column is popular.
Use semicolons to separate items in a list when the items are phrases or one of the items includes a conjunction.
Example: At 2 a.m., the diner serves bacon and eggs; ham-steak and toast; and a burger with fries.
Use a colon to introduce a list. Do not capitalize the first word of the list unless it is a proper noun or the list is a set of sentences. A colon is used to introduce a bullet-list of items, too.
A hyphen is a short, thick line, even with the top of a lowercase “x” in most typefaces. The hyphen is not a dash, though years of typing taught students they were the same.
When a compound modifier precedes a noun or follows a conjunction of “to be” in a sentence, use a hyphen to link the modifiers.
Example: The little-known writer was brilliant nonetheless.
Use a hyphen to split a word across lines of text only at a syllable. Most wordprocessors do not hyphenate automatically. Avoid hyphenation in manuscripts and when columns are narrow.
Parentheses ( ( ) )
Parentheses can replace appositives, implying more important revelations than commas.
Example: Sally Javich (the rich, rich woman next door) founded several businesses.
Use the ampersand under two conditions: the name of an organization or to identify the co-writer of a script. In other instances, use “and” to combine ideas.
Dashes (— / –)
Abrupt changes or a shift in the writing style might call for the use of an em-dash (—). Writers develop their own rules for dashes, but because readers expect a major event or change, use dashes sparingly. Some guides call for no spaces on either side of a dash, while others call for one on each. If you cannot type an em-dash (maybe you need to use a manual typewriter due to a power outage), two hyphens are used.
The shorter en-dash (–) denotes a range, such as 1–10. An en-dash is thinner, slightly longer, and usually lower than a hyphen. The en-dash should not serve as a line-break.
While the ellipsis looks like three periods, it is a unique punctuation symbol. An ellipsis is read as a long pause.
An ellipsis can indicate a “trailing thought,” which is when a speaker or narrator slows his or her words. If the ellipsis ends a sentence, most style guides suggest adding a period to the end.
Example: There was blood on the carpet, turning a dark crimson as it dried. There was no way… not her….
An ellipsis is often used to indicate the removal of text in order to condense a quotation. Using an ellipsis implies the text removed is unessential to the meaning of the quotation. When used in this manner, a space often appears before and after the ellipsis.
Example: As the world becomes connected via the Internet … new types of communities will form.
Brackets ([ ])
Use brackets to indicate words missing from or intentionally changed in dialogue or from a text. Do not use brackets in place of parentheses.
Example: “The [product] is likely to change the entire [ink pen] industry,” the CEO said. We cannot reveal the product’s name at this time.
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