Punctuation helps readers break writing into logical units, making it easier to follow. Punctuation includes all the conventional signs used to separate words: spaces, first-line indentation of paragraphs, blank lines, uppercase letters, and various marks or stops (commas, periods, semicolons, and so on). Punctuation is conventional rather than scientific, and has evolved over time. The earliest written languages, in fact, had no punctuation at all, writers just RANWORDSTOGETHERFORASLONGASTHEYCAREDTOWRITE (every so often a bold pioneer would introduce a reader-friendly innovation like LowerCaseLetters or spaces between words).

In the modern world punctuation is an important thing to get right in formal writing. Readers of formal writing interpret punctuation mistakes as a sign of poor education or carelessness, and in either case tend to discount the work's validity. Here Nuts and Bolts presents a brief treatment of the use and abuse of the major punctuation marks.

Choices in punctuation can greatly affect meaning. Indeed if you mess with punctuation enough you can turn the meaning upside down:

Fortunately, repunctuating doesn't usually have such drastic consequences. But punctuating properly is still a vital part of good writing, and it's something that gives students fits and starts. Here we want to focus on just a few of the most common punctuation troublespots: comma splices, semi-colons, colons, dashes, and parentheses.

Comma splices

A comma splice occurs when two independent clauses are connected by a comma:

Fix comma splices in a variety of ways. Easiest is to put each independent clause in its own sentence:

You may also use a semicolon:

A dash can sometimes do the job, especially if the second clause is short (see below for more on dashes):

A coordinating conjunction will also work:

Or subordination:

Or rewriting, to turn one of the clauses into a phrase:

Some good writing, especially in British English, uses comma splices. If both independent clauses are short and lack internal commas, you may be able to get away with a comma splice. But since they act as a red flag for most academic readers, I recommend avoiding them altogether.

Semicolons

Semicolons have two distinct functions in English sentences. First of all, they allow you to connect two independent clauses in a single sentence. Often a writer chooses to do this to achieve a more flowing effect; the semicolon tells the reader that he has encountered a full stop, but implies that there is a close connection between the two independent clauses (I for one do this a lot; it often just sounds right). Using a period to separate two independent clauses has a more conclusive effect. It forces more of a pause on the reader's part.

Second, semicolons replace commas when you write lists or series with internal commas (that is, where commas occur within one or more items). In such cases, separating the items with other commas is confusing:

To fix, make sure the main items are separated by semicolons (note where the commas are retained—within each main item):

Some people think that because semicolons look like fancy commas, and sometimes work like commas in lists, they can be used anytime a writer needs a comma but wants a fancy or formal effect. This is a mistake. Commas and semicolons have different grammatical functions. People also sometimes think semicolons are fancy colons. They are not. See the next item.

Colons

Colons may also be used to connect independent clauses when the logical link between them is immediate, as when the first clause makes a general assertion and the second clause provides an example:

You may also use colons between closely connected sentence elements other than two independent clauses, though this should be done sparingly:

In essays, colons are used most frequently to introduce quotations. If you use a colon, you need to make sure that the quotation is not integrally connected to the grammar of the introductory sentence:

Sometimes a colon is used incorrectly to introduce a list:

Again, the reason the second revision works is that the words before the colon stand by themselves as an independent clause.

Dashes

Dashes are a flexible and useful way of punctuating your writing—if not overused, they can give prose a punchy, vigorous feel. Dashes can act as semi-colons, connecting independent clauses. They can take the place of colons in introducing lists. They can serve to insert an example, and allow you gracefully to get back to the main sentence. You can also use them at any point in a grammatical structure when you feel a pause would be appropriate:

Hyphens (-) and dashes (—) are different creatures. Hyphens connect separate words into compounds (shoo-in, a run-of-the-mill transaction), or break a word at the end of a line (which should not be done in college essays):

Any word processor can produce a dash. In Microsoft Word on PCs the key sequence is CTRL + ALT + the numeric keypad's minus sign (at the far right). In Microsoft Word on Macs, the key sequence is OPTION + SHIFT + the hyphen key. However you produce it, don't put spaces on either side of the dash. (If you must denote a dash by typing two hyphens together (--), you should put spaces around them to keep them from being broken at the end of a line by a word processor.)

Dashes often come in pairs. If you want to signal an interruption in a grammatical structure with a dash, you've got to keep track of the grammatical structure, and signal the return to the main structure with a second dash. Some examples of the proper use of dashes will help to make this clear:

In each case, note that if we take out the dashes and all the words they contain, what is left stands as a complete sentence (but note that if we did this in the last sentence we'd have to add a comma after warfare).

Somewhat like colons, dashes are flexible enough to let you play with word order to create interesting sentences. You can present a list and then summarize it:

Parentheses

The proper symbols to use in English prose for parenthetical remarks are ( and ), not [] or {} (though you do use the square brackets [ and ] for putting notes within quotations). Make sure that you put spaces outside, not inside, each parenthesis: not( this ), but (this). Punctuation follows parentheses without a space.

Question marks and exclamation marks

Many students are reluctant to use question marks, but these are common and proper in academic writing. Indeed, sharp questions are one of the best ways to infuse prose with a bit of energy and to focus the reader's attention on a key point:

Exclamation marks, on the other hand, should be avoided except in the rarest of occasions, as for instance in the New York Times headline of August 15, 1945: "Japan Surrenders, End of War!" If you're reporting the end of a world war, feel free to use an exclamation mark. Otherwise, resist the temptation. As Lewis Thomas notes, exclamation marks tend to backfire.

Italics and emphasis

Italics and underlining both convey emphasis. Italics require good printing capability, while underlining is how one conveys emphasis in hand-written and typed work. For papers in our courses we prefer italics, though other instructors might feel differently. Bold face or different colors are not appropriate way to show emphasis in the text of a college essay, though you may use bold for headings of sections or figures.

Use italics for foreign words used in English writing:

There are various exceptions, however, to this rule: foreign titles, quotations entirely in a foreign language, and the many words which have entered English usage through frequent use. Consult a style guide appropriate to your discipline for detailed help.

One also uses italics for words used as words:

Using italics simply to emphasize words should be done sparingly; it's a relatively informal technique that doesn't tend to be accepted by academic readers. But for a counter-example see the passage from Brian Silver quoted above, in which the word science is italicized to give the sentence a bit of the richness of spoken English.

Emphasis with quotation marks

You can also emphasize words in certain situations by means of quotation marks—first, for a word you are using in a particular sense, calling into question, or intentionally misusing. Here is a neutral instance, in which the writer wants to signal that she is referring to a specific word used by Rousseau:

Here's a somewhat different example: "scare" quotes meant to call a word into question:

Words like supposed, so-called, would-be, ostensible, and putative can replace the quotation marks:

Other ways of presenting words may also render quotation marks superfluous:

But don't use quotation marks to emphasize words. Not this:

For more examples, visit the very funny Gallery of "Misused" Quotation Marks, http://www.juvalamu.com/qmarks/), from which these come.

Most writers know to avoid clichés ("black as night," "strike while the iron is hot," "the truth is out there"). Some writers, though, think it's okay to use a cliché if you put quotation marks around it. Nope. Pointing out that you know a cliché is a cliché does not immunize you against your reader's impatience—actually, it will likely make him even more dissatisfied. If you were clever enough to know you were using a cliché, why weren't you clever enough to write something more creative in the first place?

Single quotation marks

Certain scholarly disciplines, for instance philosophy, require the use of single quotation marks to denote a term used as a term (or "term qua term," as some academics love to say):

If you're not sure what a particular teacher expects, ask.

Emoticons

The recent rise of informal exchanges like email and online chat has led ever-inventive people to devise "emoticons," keyboard equivalents to the kinds of inflection that voice communication is capable of. Emoticons (and the related category of abbreviations) are a way to add a virtual tone of voice to written messages, as a sampling suggests:

Emoticons are not generally appropriate in academic writing. :-{

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