Many of the basic rules of punctuation are probably second nature to you, and so you know the common uses of periods, question marks, and other marks. In this chapter, we’ll discuss others, including many we use every day, about which you may not be certain. If you need help with the grammatical terms, see the glossary or the index.

We won’t attempt to explain the various and conflicting rules of punctuation in the several different systems for documenting research: MLA, APA, Chicago, and others. For those, consult the relevant guidebooks and websites. In this chapter, when we use quotations in examples, we omit citations.

We’ll start with an easy one.



The U. S. Postal Service now requests all capital letters and no punctuation in addresses on envelopes:






Addresses like this are easier for their mechanized sorters to read (http://pe.usps.com/BusinessMail101?ViewName=DeliveryAddress).



Many people are confused by the uses of apostrophes showing possession. One reason for the confusion is that possessive apos- trophes are often omitted in signs: e.g., McDonalds.

The rules are, with one exception, easy:


  • Apostrophes show contraction of personal pronouns and verbs; of verbs and not; and of nouns and verbs:


Heather’s car—its gone, isnt it? Heather’s upset, isn’t she?

  • Possessive pronouns (like his, hers, its, yours, and theirs) never contain apostrophes. We are particularly likely to forget this when we’re using its (the possessive pronoun) and it’s (the contraction for it is).


  • Plural possessives that end in –s take an apostrophe and no additional s: supervisors’, librarians’, soldiers’.

Plurals that don’t end in –s take both the apostrophe and

–s to show possession: media’s, criteria’s.


  • There is no consensus on punctuating some possessives. Some authorities (like the Modern Language Association, and Strunk and White) call for –’s after all singular nouns to form possessives, including nouns that end in –s: Clemens’s, Dickens’s, Jesus’s.

Other authorities (like the Associated Press Stylebook and the American Psychological Association) omit the final –s in




those possessives: Clemens’, Dickens’, Jesus’. Find out which style you’re required to use and learn it.


  • Similarly, some authorities call for apostrophes to make certain unusual plurals:


He wants to earn all A’s and B’s this semester. He prefers the jazz from the 1940’s.


More and more, it has become acceptable to omit the apostrophes here: He earned As and Bs; the 1940s. But used carelessly, the omission can be momentarily confusing. For example, the plural As could be confused with the conjunction as. Follow your teachers’ (or supervisors’) preferences on these.



The Parenthetical Commas

Commas often come in pairs, like parentheses, and these pairs have a good many uses. In general, we can use them where we might use a pair of parentheses (or a pair of dashes).

With parenthetical commas, the most common and serious error is forgetting the second comma. Don’t do that.


  • Put a pair of commas where you could put parentheses. For example, put a pair of commas around an appositive:


Mr. Smith (the principal) went to talk to the family. Mr. Smith, the principal, has returned.


  • Put a pair of commas around a parenthetical comment (one that interrupts the sentence):



That Bliebermeier boy (whom I’ve pointed out before) is a curious kid.


That Bliebermeier boy, the one I mentioned previously, has been staring at me.


  • Place commas around states (in city-state phrases) and years (in month-day-year phrases):


Salem, Massachusetts, is my favorite city. Salem, Massachusetts, USA, is my favorite city.


October 1939 is when my grandfather was born. [No commas are necessary.]


October 31, 1938, is the day the Martians landed in Grover’s Mill, New Jersey, and abducted Orson Welles.


  • A pair of commas typically encloses adjectives that follow a noun:


The audience, skeptical and snide, refused to believe my story about Orson Welles.


Single Commas

For several reasons, it’s easy to be confused about single commas. Unlike most punctuation, commas have a variety of uses, and some of those uses are optional. Different professions and disciplines (like journalism) have their own rules about some uses.

We’ll explain a set of common uses.


  • Use a comma after a coordinating conjunction that joins two independent clauses:




He got the job at the bookstore, and he means to keep it. He intended to keep the job, but then he found a better one.


We’re allowed to omit the comma if the clauses are short and easy to understand without it:


He’s employed and he means to stay employed.


  • In a sentence that begins with a subordinate clause, add a comma at the end of the subordinate clause:


Because Mortimer was late, the boss docked his pay. Before he docked Mortimer’s pay, the boss spoke with him.


If the subordinate clause is short (no more than three or four words long), the comma may be omitted. If we write the sentences above with the independent clause first, no comma is necessary.


The boss docked Mortimer’s pay because he was late. The boss spoke with Mortimer after he docked his pay.


  • Use a comma whenever you need one for clarity. Consider this sentence:


WRONG: Some authorities (like the Modern Language Association and Strunk and White) call for –’s after all singular nouns to form possessives.


The phrase the Modern Language Association and Strunk and White is momentarily confusing: Strunk and White might be read as one authority or two. The comma prevents confusion:



RIGHT: Some authorities (like the Modern Language Association, and Strunk and White) call for –’s after all singular nouns to form possessives.


  • Here’s a general rule for single commas that’s helpful: Never place just one comma between the subject and verb of the sentence:


WRONG: Nancy, is the best treasurer we’ve ever had. [Nancy is the subject, so no comma is needed.]


WRONG: Nancy, the treasurer is not here today.

[Two commas are needed around the treasurer, which is an appositive.]


RIGHT: Ed, did you know that Nancy is the treasurer? [This is correct because Ed is a noun of direct address, not the subject.]


  • We use commas to separate items in a series:


His favorite necktie is blue, green, red, and gray.


But there is disagreement about that last comma (the one before and), which is known as the serial comma (and also as the Oxford comma and that infernal comma). Some authorities leave it out unless it’s necessary for clarity. Others prefer to use it consistently. Learn which style your teacher or editor prefers.


Commas and Non-restrictive Modifiers

Use commas around non-restrictive modifiers, including clauses. This point may call for a bit of review:




Restrictive clauses (you’ll recall) are adjectivals that contain necessary information that helps to define the noun; they restrict (or narrow down) the meaning of the modified noun to something more specific. They are never enclosed in commas.

Non-restrictive clauses don’t narrow down, or restrict, the meaning of the noun; they simply provide supplementary information. They are always enclosed by commas.


Restrictive: All politicians who are crooks should be jailed.


Non-restrictive: All politicians, who are crooks, should be jailed.


The first example above says something about only those specific politicians who are crooks. The second says that all politicans should be jailed because they are all crooks.

The commas mark the difference in meaning. (Notice that you could also use a pair of parentheses in the second sentence, instead of commas.)



These are generally easier than commas: We use them in only a few cases.


  • Use a semi-colon—and no coordinating conjunction—to join two independent clauses into one sentence:


Jill likes the human anatomy class; she doesn’t need it for her major, however.


If both clauses are simple and brief, and neither contains commas, you are allowed to join them with a comma:



It’s not the heat, it’s the humidity.


  • Use semi-colons to join two or more groups of words if at least one of the groups contains commas:


Your supervisor, Mr. Smith, will be here Tuesday; Ms. Jones, his assistant, will be here Wednesday; and you, Bob, should be here every day.


The hideous creature had fangs, tentacles, and a drooling maw; wings, claws, and piercing eyes; and blond, wavy hair.



As with semi-colons, we use colons in only a few cases:


  • Use a colon after a complete sentence to introduce a list, a clause, or a quotation:


Successful students have certain traits: patience, determination, ambition.


Successful students have certain habits: they plan their work, they organize carefully, and they look for ways to improve their plans and organization.


Steve quoted Mark Twain: “Perfect grammar—persistent, continuous, sustained—is the fourth dimension, so to speak; many have sought it, but none has found it.”


Notice that in each example above, a word before the colon (traits, habits, quoted) announces or anticipates the words that follow it.

We are also allowed to place the list or phrase first, and then follow it with a colon and complete sentence:




Patience, determination, ambition: These are the qualities of a successful student.


In other words, a complete sentence must appear to the left or the right of a colon, or in both positions.


  • A colon never follows words like include, such as, or like:


WRONG: A successful student’s qualities include: patience, determination, ambition.


RIGHT: A successful student’s qualities include patience, determination, ambition.


WRONG: I want to take courses such as: biology, astrono- my, and physics.


RIGHT: I want to take courses such as biology, astronomy, and physics.


  • A colon should appear at the end of a sentence that introduces a block quotation. (See the example in the section on ellipses and square brackets.)


  • When you introduce examples, with or without a colon, punctuate carefully. Both of these are correct:


He used many odd words (for example, flabbergast, discombobulate, and others).


He used many odd words: for example, flabbergast, discombobulate, and others.


If you wanted to use e.g. instead of for example in either of the sentences, the punctuation would not change:



He used many odd words (e.g., flabbergast, discombobu- late, and others).




It’s easy for Americans to be confused about quotation marks because British books, periodicals, and websites use them differ- ently. (The British are wrong, but don’t tell them we said so.)


  • You never put quotation marks around the title of your own short story or essay, although you may put it in boldface type if you like. If you refer to your own work after it’s published, then you include the quotation marks.


  • When referring to the short works of others (e.g., short stories and poems, articles, songs, or a web page within a larger site), enclose them in quotation marks: “The Raven,” “The Star- Spangled Banner,” “Frequently Asked Questions.”


  • Titles of long works (books, newspapers, magazines, movies, plays, or entire websites) should be italicized: The Lord of the Rings, The New York Times, The Best Years of Our Lives.

Before word processing and the personal computer, writers using typewriters underlined titles of long works—The Lord of the Rings—and some writers continue to do this. But now computers make italics so easy that we can leave this old- fashioned practice behind. Underlining is now usually reserved for graphic design purposes, as in some résumé formats.

Many publications and websites still follow the old journalistic practice of enclosing titles of long works in quotation marks: “The Lord of the Rings.” (In the long-ago past, when newspaper compositors set type by hand or with machines like Linotypes, switching from roman type to italics




and back was uneconomically time-consuming.) If you’re writing for one of those outlets, follow their rules.


  • Commas and periods always go to the immediate left of quotation marks—,” .”—and never to the immediate right. Colons and semi-colons never go to the immediate left of the final quotation marks.

Question marks and exclamation points go to the left only if they are part of the quotation or title:


Louis Jordan wrote the song “Is You Is or Is You Ain’t My Baby?”


Didn’t he also write “Baby, It’s Cold Outside”?


Notice that the first example above is a declarative sentence, but it has no period at the end. Only one final punctuation mark is required.


  • After an attribution of a quotation (e.g., Paine wrote), commas and quotation marks follow the verb (wrote, stated, observed, and others) unless one or more words follow the verb. Notice how the punctuation changes as the attribution or its placement changes:


Thomas Paine wrote, These are the times that try men’s souls.”


Paine wrote that These are the times that try men’s souls. These are the times,” Paine wrote, that try men’s souls.

These are the times that try men’s souls,” as Thomas Paine wrote.



Did Paine write “These are the times that try men’s souls”?


  • Single quotes are used inside double quotes. Commas and periods are placed inside single quotes:


Irving Berlin wrote “God Bless America.”


The announcer said, “Irving Berlin wrote such popular songs as ‘White Christmas,’ ‘There’s No Business like Show Business,’ and ‘God Bless America.’”


Notice the three quotation marks after the period above.

See the example of block quotations in the section on ellipses and square brackets.



We are permitted to delete words from direct quotations if we use ellipses (three spaced periods) to tell our readers (1) that words have been deleted and (2) where the deleted words were.

Similarly, we can add words to quotations by enclosing the additions in square brackets.

The following sentence, which contains a quotation, uses both ellipses and brackets:


In his book The Great Movies, film critic Roger Ebert writes that The Maltese Falcon is “[a]mong the movies we not only love but treasure. ”


In the original text by Ebert, the quoted words were at the beginning of a sentence, so the writer has used brackets to make the first letter of among lowercase. (The brackets for changing the capital are not always required, depending on the style guide you’re using.)




Also notice that after the three ellipses, there is a fourth period to end the sentence.

Here’s a second example, using a block quotation from Garry Wills’s book Certain Trumpets: The Nature of Leadership. A block quotation is typically four or more lines long.

Here, the writer introduces the quotation from Wills with a complete sentence (Wills explains . . . ) that ends in a colon. In the block quotation, the writer has deleted words with ellipses and inserted a comment in square brackets:


Wills explains why radicals of the 1930’s and 1940’s objected to moderate leaders like Eleanor Roosevelt:


Those who reject the moderate leader because only a radical protest is “authentic” [a term describing protest that is believed to be sincere and effective] will never understand the need more ordinary people have for help to meet life’s daily problems. Nor do they see how moderates alter power by making it more responsibleEleanor

Roosevelt was “naïve” in the eyes of ideologues who did

not understand her extraordinary appeal.


As this example illustrates, block quotations have a wider left margin and are not enclosed in quotation marks. Within block quotations, use double quotations, as above.



When we write about words as words (i.e., as examples of language), those words should be italicized, although quotation marks are often used and are also correct.


When you speak of carrying something from one point to another, do you ever say tote, lug, or schlep?



You can use quotation marks in this sentence, but it complicates the punctuation:


Do you ever say “tote,” “lug,” or “schlep”?



It was long the rule to place a period after every initial letter in abbreviations like these: U.S.A., U.K., U.N., N.A.S.A.

Today in most (but not all) publications and contexts, we omit the periods: USA, UK, UN, NASA are now widely acceptable.

We still put periods after abbreviations that include the first letter and later letters in the same word: Mr., Mrs., Ms., Dr., Sen. (The British omit the periods in some of these, but we’ve already warned you about them.)



You know most of the rules already, but here are a couple that may be new to you.

Capitalize The in the titles of books, newspapers, and other publications only if the word is part of the title. Thus we write The New York Times, but the Chicago Tribune and the New York Daily News.

In titles, it’s usual to capitalize the first word, all nouns and verbs, and all adjectives and adverbs, but practices vary consider- ably. You’ll have to consult the relevant style guide.

And do we write earth or Earth? Do we write sun and moon, or Sun and Moon? Internet or internet? Not even a dictionary can help with some words. Again, consult your style guide. Or make up your own mind and be consistent about it.







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Interactive Grammar Book by Sushumna Rao Tadinada; Professor Moustapha Diack; and Diola Bagayoko, Ph.D. is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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