Whole books—lots of them—have been written about punctuation, and I believe it would take an entire semester to teach writers all the ins and outs of parentheses, the slips and slides of slashes, hyperbolic reactions of the language mavens to simple hyphens.
In one of my favorite of those books on the subject, Karen Elizabeth Gordon defines punctuation rhetorically: “What is it, after all, but another way of cutting up cutting up time, creating or negating relationships, telling words when to take a rest, when to get on with their relentless stories, when to catch their breath?”
Here is a brief primer on this confounding subject, spiced with some of my favorite quotes from Gordon and others. (Gordon herself had so much to say on the subject that she wrote two separate editions of The Well-Tempered Sentence, which I refer to here as Well-Tempered One and Well-Tempered Two.)
The period (.)
The period is used for ending declarative or imperative sentences, for indicating decimals, for punctuating bulleted lists, for separating reference entries in bibliographies, for following initials, and for truncating words into abbreviations.
Karen Elizabeth Gordon, Well-Tempered Two: “A period can pirouette and still make its point.”
The semicolon (;)
The semicolon is stronger than a comma, weaker than a period. It has two major roles—you might even say it has a bit of a split personality or a case of confused identity. First, it links two complete sentences (or “independent clauses”) that may have a common theme or other relation to each other. Second, it acts as a supercomma in a complicated list whose elements have internal commas. In its more minor role, it can also separate elements in a reference or bulleted list.
The colon (:)
A colon, usually preceded by a complete sentence, introduces a second sentence or phrase—or a list or a quote—that illustrates, restates, elaborates, or makes sense of the first sentence. Colons are also used to express ratios and time, and they are used in certain reference notation.
H.W. Fowler, in A Dictionary of Modern English Usage: the colon “delivers the goods that have been invoiced in the preceding words.”
BEWARE: Various style books (Chicago, AP, etc.) advocate slightly different uses of the colon, so if you are writing for publication copy editors will usually apply the style of the publication.
The comma (,)
The comma collects groups of words into phrases, separates elements of a list, and places badly needed pauses between parts of sentences. When combined with a coordinate conjunction (and, but, yet, for, so, or, nor), it can separate two independent clauses that would otherwise require a period or semicolon as punctuation.
Karen Elizabeth Gordon, in Well-Tempered One: “What is a comma but a claw rending the sheet, the asthmatic’s gasp?”
The question mark (?)
Question marks are almost as easy to use as periods. (In fact, most of us use them correctly.) A question mark simply ends a sentence that asks a question rather than making a direct statement. It gets tricky when questions are imbedded within larger sentences. Confusion arises about how to combine them with other punctuation marks. (If a quotation is itself a question, put the question mark inside quotes; if the quotation is part of a larger question, put the question mark outside quotes.)
The exclamation point (!)
The name of this mark suggests when it should be used—for an exclamation of surprise or excitement. Keep in mind that too many of these make writing look silly or just amateurish.
Lynn Truss, in Eats, Shoots & Leaves, notes that the exclamation is known in the British newspaper world as a screamer, a gasper, a startler, or a dog’s collar.
Karen Elizabeth Gordon, Well-Tempered Two: An exclamation mark leaps onto the page in place of flaming eyes, thumping first, a defiant thrust of chin.”
The ellipsis (and….)
An ellipsis is properly used when quoted material is deleted from a sentence or from a passage. It can also be used at the end of a sentence to allow a thought to trail off, or to even suggest a little mystery. This is more appropriate in informal writing, like letters or journal writing. Ellipses (note the plural) are cropping up more and more in emails as shorthand for “I could go on, but will spare you.”
Punctuation within sentences (clarifying groups of words)
Parentheses ( ( ) ) & Dashes (—)
Parentheses and dashes allow you to take a break from your sentence, go off on a brief tangent, or give a quick example without really leaving your line of thought behind. As such they are stronger than commas, but weaker than a semicolon. They can be used to set off a phrase or an independent clause; they also may indicate a break in a train of thought or a segue. (An entire sentence, like this one, can be set off by parentheses, in which case you are taking a break within the whole paragraph.)
Oftentimes parentheses, dashes, and commas are equally correct, they just set the thought off to a different degree. Likewise, a semicolon and a dash may be equally correct. But a dash may be more appropriate for occasions when the connection between two clauses is less direct, more fractured.
Copy editors distinguish between en-dashes (used for ranges, or compound adjectives that contain proper nouns) and em-dashes (also called the punctuation dash, defined above).
Lynn Truss, in Eats, Shoots & Leaves : “As they sit on the page, it seems to me that the parentheses half-remove the intruding aside, half-suppress it, while the dashes warmly welcome it in, with open arms.”
The quotation mark (‘/’ or “/”)
Pairs of quotation marks are used to set off—you guessed it!—quoted material. They are also used by some publications in lieu of italics to set off titles of books, plays, recordings, or other works. Single quotes are used only when there is quoted material within other quoted material. Reserve quotation marks for real quotations, resisting the urge to use them for irony or to distance yourself from factual inaccuracy.
Many mechanical errors arise from confusion over which punctuation marks go inside quotation marks and which go outside. (This confusion is made worse by the fact that British English uses different rules.) OK, so what goes in, what goes out?
- Question mark and exclamation mark—it depends
Lynn Truss, in Eats, Shoots & Leaves: “[Quotation marks are] sometimes used by fastidious writers as a kind of linguistic rubber glove, distancing them from vulgar words or clichés they are too refined to use in the normal way.”
The ellipsis ( … or ….)
An ellipsis is used when quoted material is deleted from a sentence or from a passage. As explained above, in more informal writing it can also be used at the end of a sentence to allow a thought to trail off, or suggest a little mystery.
When material is removed from the beginning or the middle of a sentence, three dots are used; when material is removed from the end of a sentence, the three dots follow a period. In some publications this looks like this: [. …]. In other publications the four dots are evenly spaced.
An ellipsis in dialogue, when a speaker either abruptly stops or is interrupted; here, dashes are preferred over (because nothing is actually deleted). Example:
Chloe heard her mother’s footsteps and shrank from the cookie jar. “I was just trying—“
“Out of the kitchen and on to your homework,” her mother said.
Lynn Truss, in Eats, Shoots & Leaves: “The ellipsis is the black hole of the punctuation universe, surely, into which no right-minded person would willingly be sucked.”
The apostrophe (’)
The apostrophe has two main functions: to mark the omission of one or more letters (as in doesn’t for does not), and to indicate possessives of nouns and some pronouns (the teacher’s pet). In certain cases, it is allowed to mark plurals.
NOTE: The Associated Press has a weird rule for what it calls “descriptive phrases”: Do not add an apostrophe to a word ending in s when it is used primarily in a descriptive sense: citizens band radio, a Cincinnati Reds infielder, a teacher college, a Teamsters request, a writers guide.
The AP gives this “memory aide:” the apostrophe usually is not used if for or by rather than of would be appropriate in the longer form: a radio band for citizens, a college for teachers, a request by the Teamsters, a guide for writers. An s is required, however, when a term involves a plural word that does not end in s: a children’s hospital, a people’s republic, the Young Men’s Christian Association.
Then there are what AP calls “descriptive names”: Some governmental, corporate and institutional organizations with a descriptive word in their names use an apostrophe; some do not. Follow the user’s practice: Actor’s Equity, Diners Club, the Ladies’ Home Journal, the National Governors’ Association.
The hyphen (-)
With compound modifiers and compound nouns, hyphens can eliminate a considerable amount of confusion. Lynn Truss’s examples from Eats, Shoots & Leaves makes this point well; notice how hyphens can alter the meaning of these noun phrases: the little-used car v. the little used-car, the superfluous-hair remover v. the superfluous hair-remover, the pickled-herring merchant v. the picked herring-merchant, the two-hundred-odd members of the Conservative Party in Parliament v. the two hundred odd members.”
NOTE: We do not use hypens with –ly adverbs when they appear in compound modifiers. But watch out: some nouns (friendly) end in –ly and if they are part of a compound they need to be hyphenated: the friendly-fire accident.
Lynn Truss, in Eats, Shoots & Leaves: The hyphen “keeps certain other words neatly apart, with an identical intention. Thus the picked-herring merchant can hold his head high, and the coat-tail doesn’t look like an unpronounceable single word.”
John Benbow (once stylebook editor of the Oxford University Press): “If you take hyphens seriously, you will surely go mad.”
Karen Elizabeth Gordon, in Well-Tempered Two: “The promiscuous hyphen is game for liaisons with anyone.”
The last word
Lynne Truss, in Eats, Shoots and Leaves, offers this metaphor to keep your marks straight: “In the family of punctuation, where the [period] is daddy and the comma is mummy, and the semicolon quietly practices the piano with crossed hands, the exclamation mark is the big attention-deficit brother who gets overexcited and breaks things and laughs too loudly.”