Punctuation Tips

Punctuation Tips


This mark represents omitted letters in contractions, in dates to show omitted numbers, and to show possession. Apostrophes also show up in Irish last names and indicate the plurals of letters and words. Example: O'Malley resolved in January '05 that she would follow her instructor's advice, mind her p's and q's, and wouldn't misuse apostrophes.


These marks are primarily used to insert corrections, editorial comments and clarifications into quoted material, and appear in math and chemistry formulas. Example: Sabatier was writing at a time [1840-1865] when it was still possible to believe that government was unnecessary.


Use a colon to introduce a list, example, or long quotation, or for text that explains a statement preceding a colon. The colon is also used to separate hours and minutes in designating time of day, in ratios, to separate titles and subtitles of books and films, and in scripts to separate speakers from their dialogue. Insert one space after a colon. The text preceding a colon usually forms a complete sentence. The first word after a colon is lowercase if it is part of a list and usually lowercase when it starts a complete sentence; however, when the sentence is long and dramatically different than what preceded the colon, it is typically capitalized. Example: In Chris's speech at 3:30 p.m., he gave three reasons for choosing Lane: quality, affordability, and accessibility.


The comma is undoubtedly the most confusing, misused, and controversial of all punctuation marks. Below is a concise overview: for thorough information, refer to a book-length style guide.


Use a comma before a conjunction (such as "and") if the two clauses could stand as separate sentences. Do not use a comma if the subject of the two clauses is the same and is not repeated in the second. Examples: The students will visit the coast, and they also hope to visit a forest ecosystem [a comma is required in this version of the sentence]. The students will visit the coast and a forest ecosystem [there should absolutely not be a comma in this version].


Use day of the week, comma, then month and date, comma, and finally year when needed. Set off the year with commas in month-date-year combinations embedded in a sentence. Do not separate month-year combinations by commas. Use an apostrophe to indicate numbers that are left out, and use numbers without suffixes such as "st," "nd," "rd" or "th" except in street names. Do not use an apostrophe before an "s." Examples: Voters approved formation of Lane on October 19, 1964, by district election. When she mentioned the '90s, she was referring to the 1890s.

interruptions, parenthetical expressions or expressions in apposition

Use commas to set apart clauses from the rest of the sentence. Example: Even the editor, who really knew his onions when it came to punctuation, sometimes agonized over commas.

introductory words or phrases

A comma is often used after an introductory word or phrase. Example: During the summer, she will be living in Florence, Italy.


Use commas in numbers of 1,000 or more except in these cases: street numbers, radio station frequencies, room numbers, serial numbers, telephone numbers, or years.

quotes  (Also see quotation marks in this section.)

Use a comma to introduce a complete one-sentence quote or at the end of a quote that is followed by an attribution. Do not use a comma for an indirect or partial quote. Use a colon for a quote of more than one sentence. Examples: "Study for the exam," the professor urged. She later said that the effort was worthwhile because it allowed her to "achieve a long-sought goal."

series or list 

Use commas to separate elements in a series. When the last two items in a series are joined by a conjunction, the final comma should be included if this would not result in ambiguity. Example: The department exceeded projections in March, April, May, and August.


Dashes are not hyphens—they have the specific uses outlined below. Em dashes are the length of the letter "m" and are used for dramatic emphasis—so avoid overuse. En dashes are the length of the letter "n" and are used between numbers or dates.

Em dash (—) 

The em dash is longer than an en dash or hyphen. Use an em dash to denote an abrupt change in thought, set off a parenthetical expression or introduce a summary phrase. To access the em dash on a Mac, press Option, Shift and Hyphen; with Windows, press Shift, Alt, and Hyphen. Example: Of the three entrees—salmon, spinach lasagna, or meatloaf—the last option was definitely the least appealing. Em dashes are also used to indicate missing text. A two-em dash is used to indicate missing letters in a word, and a three-em dash indicates a missing word. Example: In his testimony, Mr. B—— admitted to having embezzled funds from ———.

En dash (–) 

Use an en dash to indicate continuing or inclusive numbers in dates, times, or reference numbers. To access the en dash on a Mac, press Option and Hyphen; for Windows computers, press Alt and Hyphen. Examples: 2000–01, 8 a.m.–5 p.m., pages 12–18.


Ellipses are periods indicating an omission from a quotation or used to indicate faltering speech. Use three ellipsis points if only a part of a sentence has been omitted. Add a period before the ellipses if a sentence or more has been omitted or to end your sentence with an ellipses. It is optional whether or not to have a space before and after ellipsis points (tip: by not spacing ellipsis points, both keystrokes and space are saved). Use ellipses sparingly and only if the sentence still makes sense. Examples: The instructor...has received awards for both her teaching and her writing. Johnson's last words were: The money is hidden in the....

exclamation point 

Avoid using exclamation points in professional writing except when they appear in a direct quote. Why? Because exclamation marks are the visual equivalent of yelling at the reader. Example: When asked if exclamations were advisable in professional writing, the writing instructor animatedly answered, "No! No! No!"


Hyphens are intended for use in hyphenated words, and are different than an em dash or en dash. Hyphenate compound adjectives that precede a noun, including an age. Example: The five-year plan was the result of a two-year study.


Use parentheses to add clarifying information or an aside to the reader. When parentheses enclose a full sentence, periods and question marks should go inside the parentheses; if not a full sentence, the marks go outside the parentheses. Example: He wished (and he said this often) that he had gone with Chris to tour South America.


In addition to being the most common way to end a sentence, periods are also used in decimal numbers and web addresses. Use one space after a period (if in doubt that this is standard English usage, check the nearest book or magazine). In American English, periods always go inside quotation marks.

question mark 

This mark is used at the end of direct questions and rhetorical questions.

quotation marks 

Quoted material is enclosed in double quotation marks, and single quotation marks are used for quotations within a quotation. Periods and commas always go inside quotation marks. Other punctuation marks go inside when they are part of quoted matter and outside when they apply to a whole sentence that includes a quoted section.  Example: After class, she said, "It was Tolstoy who wrote, 'There is no greatness without simplicity,' and not Melville." Other uses of quotation marks include: to enclose words or phrases borrowed from others; to enclose definitions of words or translations of foreign words and phrases; to designate words referred to as words (italics may also be used for this purpose); and to enclose letters referred to as letters (although italics are more often used in this instance, and letters can be left undifferentiated from the surrounding text when no confusion would result).


Use semicolons to separate items in a list that already contain commas or to connect two parallel parts of a sentence. It is best to use this mark sparingly and judiciously. Think of a semicolon between sentences as a "semi-period," and think of the semicolon between items in a series as a "super comma." Example: He will be traveling to Antelope, Oregon with his wife, Jane Doe; two daughters, Peggy Deere of Cheshire and Patty Moose of Portland; and a brother, Michael Hunter of Eugene.

slash/forward slash/oblique stroke/virgule/diagonal/solidus 

This mark has more names than functions. Use it to indicate a period extending over two calendar years or to indicate alternatives. Use a slash sparingly as it is more appropriate for casual rather than professional writing, and it creates little walls in a sentence that interrupt the smooth flow of text. Example: The pass/no pass option was available when we were attending in 2003/04.