Punctuation

Colon

The colon has primarily three grammatical uses and several non-grammatical uses. Introducing a list The colon is used to introduce a list of items. The bookstore specializes in three subjects: art, architecture, and graphic design. Do not, however, use a colon when the listed items are incorporated into the flow of the sentence. Correct: The bookstore specializes in art, architecture, and graphic design. Incorrect: The bookstore specializes in: art, architecture, and graphic design. Between independent clauses when the second explains or illustrates the first The colon is used to separate two independent clauses when the second explains or illustrates the first. In such usage, the colon functions in much the same way as the semicolon. As with the semicolon, do not capitalize the first word after the colon unless the word is ordinarily capitalized. I have very little time to learn the language: my new job starts in five weeks. A college degree is still worth something: a recent survey revealed that college graduates earned roughly 60% more than those with only a high school diploma. All three of their children are involved in the arts: Richard is a sculptor, Diane is a pianist, and Julie is a theatre director. When two or more sentences follow a colon, capitalize the first word following the colon. He made three points: First, the company was losing over a million dollars each month. Second, the stock price was lower than it had ever been. Third, no banks were willing to loan the company any more money. Emphasis The colon can be used to emphasize a phrase or single word at the end of a sentence. An em dash can be used for the same purpose. In the second example below, an em dash is more common than a colon, though the use of a colon is nevertheless correct. After three weeks of deliberation, the jury finally reached a verdict: guilty. Five continents, three dozen countries, over a hundred cities: this was the trip of a lifetime. Non-grammatical uses of the colon Time The colon is used to separate hours from minutes, with no space before or after the colon. 11:35 a.m. Ratio The colon is used to express a ratio of two numbers, with no space before or after the colon. 1:3 Biblical references The colon is used in biblical references to separate chapter from verse, with no space before or after the colon. Genesis 1:31 Other references The colon is used to separate the volume from page numbers of a cited work, with no space before or after the colon. Punctuation Quarterly 4:86-89 (read as "pages 86 through 89 of volume four") Correspondence The colon is frequently used in business and personal correspondence. Dear Ms. Smith: cc: Tom Smith Attention: Accounts Payable PS: Don't forget your swimsuit.

En dash

The en dash (-) is slightly wider than the hyphen (-) but narrower than the em dash (—). The typical computer keyboard lacks a dedicated key for the en dash, though most word processors provide a means for its insertion. Span or range of numbers The en dash is used to represent a span or range of numbers, dates, or time. There should be no space between the en dash and the adjacent material. Depending on the context, the en dash is read as "to" or "through." The 2010-2011 season was our best yet. You will find this material in chapters 8-12. The professor holds office hours every Wednesday, 11:00 a.m.-1:00 p.m. If you introduce a span or range with words such as from or between, do not use the en dash. Correct: She served as secretary of state from 1996 to 1999. Incorrect: She served as secretary of state from 1996-1999. Correct: The regime's most oppressive treatment occurred between 1965 and 1970. Incorrect: The regime's most oppressive treatment occurred between 1965-1970. Scores The en dash is used to report scores or results of contests. The president's nominee was confirmed by the Senate, which voted 62-38 along party lines. UCLA beat USC 28-14 in the final game of the regular season. Conflict or connection The en dash can also be used between words to represent conflict, connection, or direction. The liberal-conservative debate. The Los Angeles-London flight. There is a north-south railway in the same area as the highway that runs east-west. Compound adjectives When a compound adjective is formed with an element that is itself an open compound or hyphenated compound, some writers replace the customary hyphen with an en dash. This is an aesthetic choice more than anything. For more on the hyphenation of compound adjectives, see here. Hyphen: She is an award-winning novelist. En dash: She is a National Book Award-winning novelist. Hyphen: It was just one of many changes in this post-Clinton era. En dash: It was just one of many changes in this post-New Deal era. Hyphen: They were a bunch of college-educated snobs. En dash: They were a bunch of prep school-educated snobs. Hyphen: He submitted his manuscript to a print-only publisher. En dash: He submitted his manuscript to an e-book-only publisher.

Ellipses

An ellipsis is a set of three periods ( . . . ) indicating an omission. Each period should have a single space on either side, except when adjacent to a quotation mark, in which case there should be no space. Informal writing In informal writing, an ellipsis can be used to represent a trailing off of thought. If only she had . . . Oh, it doesn't matter now. An ellipsis can also indicate hesitation, though in this case the punctuation is more accurately described as suspension points. I wasn't really . . . well, what I mean . . . see, the thing is . . . I didn't mean it. Like the exclamation point, the ellipsis is at risk of overuse. In quoted material Ellipses are most useful when working with quoted material. There are various methods of deploying ellipses; the one described here is acceptable for most professional and scholarly work. The following examples are based on a paragraph from Henry David Thoreau's Walden: I learned this, at least, by my experiment: that if one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours. He will put some things behind, will pass an invisible boundary; new, universal, and more liberal laws will begin to establish themselves around and within him; or the old laws be expanded, and interpreted in his favor in a more liberal sense, and he will live with the license of a higher order of beings. In proportion as he simplifies his life, the laws of the universe will appear less complex, and solitude will not be solitude, nor poverty poverty, nor weakness weakness. If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them. Ellipses at the beginning of a quotation It is rarely necessary to use ellipsis points at the beginning of a quotation, even if the quotation begins mid-sentence. It is also usually acceptable to change the capitalization of the first word of the quotation to match the surrounding material. (When a change in capitalization must be acknowledged, you should use brackets, as explained here.) "If one advances confidently in the direction of his dreams," writes Thoreau, "he will meet with a success unexpected in common hours." Moreover, Thoreau claims that "in proportion as he simplifies his life, the laws of the universe will appear less complex." Quotations placed in the middle of a sentence When a quotation is included within a larger sentence, do not use ellipsis points at the beginning or end of the quoted material, even if the beginning or end of the original sentence has been omitted. Correct: When Thoreau argues that by simplifying one's life, "the laws of the universe will appear less complex," he introduces an idea explored at length in his subsequent writings. Incorrect: When Thoreau argues that by simplifying one's life, ". . . the laws of the universe will appear less complex, . . ." he introduces an idea explored at length in his subsequent writings. Quotations placed at the end of a sentence When a quotation is placed at the end of a sentence, but the quoted material is only part of a larger sentence, authorities differ on the use of ellipsis points. The Chicago Manual of Style allows the use of a sentence-terminating period; the MLA Handbook for Writers of Research Papers requires ellipsis points. Chicago style Thoreau argues that by simplifying one's life, "the laws of the universe will appear less complex." Could anyone other than Thoreau have written, "If you have built castles in the air, your work need not be lost"? MLA style MLA style places the sentence-terminating period immediately after the last word of the quotation, even though a period does not occur there in the original material. The three ellipsis points are then placed after this sentence-terminating period. Thoreau argues that by simplifying one's life, "the laws of the universe will appear less complex. . . ." Could anyone other than Thoreau have written, "If you have built castles in the air, your work need not be lost . . ."? When using MLA-style parenthetical references, the sentence-terminating period is placed outside the parenthetical reference. Thoreau argues that by simplifying one's life, "the laws of the universe will appear less complex . . ." (152). Ellipses for omitted material within a single quoted sentence Use ellipsis points to show omission within the quotation. Omit any punctuation on either side of the ellipsis, unless the punctuation is necessary to make the shortened quotation grammatically correct. "I learned this . . . : that if one advances confidently in the direction of his dreams, . . . he will meet with a success unexpected in common hours." In the example above, the colon in the original is needed to introduce the thing that Thoreau learned. The comma after "dreams" is necessary to separate a dependent clause from an independent clause. Ellipses for omitted material spanning two or more sentences When a quotation is presented as a single sentence made up of material from two or more original sentences, ellipses should be used for all omitted segments. Thoreau believes that "if one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, . . . he will live with the license of a higher order of beings." When quoted material is presented as multiple sentences, four dots should be used for omissions between two or more original sentences; three dots should be used for omissions within a single original sentence. In the example below, MLA style requires an ellipsis at the end of the quotation, indicating that a portion of the original sentence has been omitted. Chicago style would omit the final ellipsis and terminate the sentence with a single period. Thoreau notes: "I learned . . . that if one advances confidently in the direction of his dreams, . . . he will meet with . . . success. . . . He will put some things behind, will pass an invisible boundary. . . . In proportion as he simplifies his life, the laws of the universe will appear less complex. . . ."

Hyphen

For most writers, the hyphen's primary function is the formation of certain compound terms. The hyphen is also used for word division, which is briefly explained here. Never use a hyphen in place of an en dash or an em dash. Compound terms Compound terms are those that consist of more than one word but represent a single item or idea. They come in three styles. Open (or spaced) compounds are written as separate words. printing press car wash chief of staff Hyphenated compounds use hyphens between the words. eye-opener check-in free-for-all Closed (or solid) compounds are written as a single word. lifestyle bookstore whodunit Compound nouns Compound nouns are the easiest to deal with: most of them can be looked up in a good dictionary. Keep in mind, though, that many compound nouns start out spaced or hyphenated before eventually becoming solid, with dictionaries often lagging behind current usage. Compound verbs Compound verbs (e.g., waterproof, highlight, rubber-stamp, nickel-and-dime) also are typically included in a good dictionary. Compound adjectives The most difficult compound terms to deal with are the compound adjectives. For one thing, most of them will not be found in any dictionary. For another, whether they are hyphenated or not depends on their position within a sentence. Whether to hyphenate or not is often a matter of style. Some basic guidance is offered below. For more detailed guidance, the current (16th) edition of The Chicago Manual of Style includes a useful table of rules for all manner of compounds. Two or more words that collectively act as an adjective should be hyphenated when they appear immediately before the noun they modify. This helps prevent misreading. Voters are fed up with this do-nothing congress. The victim is being described only as a twenty-five-year-old man. Does this come with a money-back guarantee? The house comes with a state-of-the-art security system. Though the one-bedroom condos are sold out, we still have several two-, three-, and four-bedroom units available. The major exception is when the compound adjective begins with an adverb ending in -ly. In that case, since a misreading is unlikely, the hyphen is unnecessary. If the -ly adverb is part of a larger compound adjective, use a hyphen. This is a poorly produced movie. He followed up with a not-so-poorly-produced sequel. Forming compounds with an en dash Certain particularly complex compounds can be formed with an en dash rather than a hyphen, as explained here. Word division In professionally printed material (particularly books, magazines, and newspapers), the hyphen is used to divide words between the end of one line and the beginning of the next. This allows for an evenly aligned right margin without highly variable (and distracting) word spacing. The rules for such word division are beyond the scope of this guide; they are also beyond the needs of most writers. If you are writing for a publication that requires it, the word division will be handled by the typesetter. Your word processor's default setting, which is to avoid word division at the end of each line, is appropriate for nearly all of your writing—academic, business, or personal.

Parentheses

Parentheses (always used in pairs) allow a writer to provide additional information. The parenthetical material might be a single word, a fragment, or multiple complete sentences. Whatever the material inside the parentheses, it must not be grammatically integral to the surrounding sentence. If it is, the sentence must be recast. This is an easy mistake to avoid. Simply read your sentence without the parenthetical content. If it makes sense, the parentheses are acceptable; if it doesn't, the punctuation must be altered. Correct: The president (and his assistant) traveled by private jet. Incorrect: The president (and his assistant) were expected to arrive by 10:00 a.m. Placement of other punctuation When a parenthetical sentence stands on its own, the closing punctuation mark for the sentence is placed inside the closing parenthesis. The idea that theoretical physics can be taught without reference to complex mathematics is patently absurd. (But don't tell that to the publishers of such mathematics-free books—or the people who buy them.) When parenthetical content occurs at the end of a larger sentence, the closing punctuation mark for the sentence is placed outside the closing parenthesis. After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction). When parenthetical content occurs in the middle of a larger sentence, the surrounding punctuation should be placed outside the parentheses, exactly as it would be if the parenthetical content were not there. We verified his law degree (Yale, class of 2002), but his work history remains unconfirmed. When a complete sentence occurs in parentheses in the middle of a larger sentence, it should neither be capitalized nor end with a period—though a question mark or exclamation point is acceptable. We verified his law degree (none of us thought he was lying about that) but not his billion-dollar verdict against Exxon (how gullible did he think we were?). Specialized uses Numbered or lettered lists should use a pair of parentheses to enclose the numbers or letters. Please submit the following four items with your application: (1) a cover letter, (2) a resume, (3) a college transcript, and (4) a list of professional references. Time zones are usually enclosed in parentheses following the time. The conference call will be held at 9:00 a.m. (EST). Area codes are sometimes enclosed in parentheses. If you have any questions, please call me at (212) 555-7875. Short translations in unquoted text can be placed in parentheses. (Use brackets for translations in quoted text.) His knowledge of Portuguese is limited to obrigado (thank you) and adeus (goodbye). In some writing, a person's year of birth and year of death are provided in parentheses when the person is first mentioned. If there is uncertainty about the year, a question mark should follow it. Note that an en dash, rather than hyphen, is used between the years. Guido Cavalcanti (1255?-1300) had a profound influence on the writings of Dante. Abbreviations and acronyms On the first use of an abbreviation or acronym that might not be understood by your readers, the full term can be provided in parentheses. John Smith has been appointed CKO (chief knowledge officer) of the merged company. In reverse, an acronym or abbreviation can be provided in parentheses upon its first use, and then used in place of the full term in the remainder of the document. In conducting the study, researchers relied on positron emission tomography (PET) and, to a lesser extent, functional magnetic resonance imaging (fMRI).

Apostrophe

The apostrophe ( ' ) has three uses: contractions, plurals, and possessives. Contractions Contractions (e.g., let's, don't, couldn't, it's, she's) have a bad reputation. Many argue that they have no place at all in formal writing. You should, of course, observe your publisher's or instructor's requirements. An absolute avoidance of contractions, however, is likely to make your writing appear stilted and unwelcoming. If you are unsure where to insert the apostrophe when forming a contraction, consult a good dictionary. Avoid the most common contraction-apostrophe error: the contraction of it is is it's; without the apostrophe, its is the possessive form of it. Example: It's often said that every dog has its day. In informal writing, it is acceptable to indicate a year with only the last two digits preceded by an apostrophe (e.g., the class of '85, pop music from the '80s). Plurals The apostrophe is seldom used to form a plural noun. Incorrect: Since the 1980's, the Thomas's, both of whom have multiple PhD's, sell old book's and magazine's at the fair on Saturday's and Sunday's. Correct: Since the 1980s, the Thomases, both of whom have multiple PhDs, sell old books and magazines at the fair on Saturdays and Sundays. The rare exception to the rule is when certain abbreviations, letters, or words are used as nouns, as in the following examples. Unless the apostrophe is needed to avoid misreading or confusion, omit it. He received four A's and two B's. We hired three M.D.'s and two D.O.'s. Be sure to cross your t's and dot your i's. Do we have more yes's than no's? For this last example, the trend is to instead write yeses and noes. Possessives The formation of possessives is treated in different ways by different authorities. The rules below are based on The Chicago Manual of Style, 16th edition, and are appropriate for most writing. Associated Press style, used by most newspapers, is slightly different. See the essay on style for more information. The general rule for forming possessives The general rule is that the possessive of a singular noun is formed by adding an apostrophe and s, whether the singular noun ends in s or not. the lawyer's fee the child's toy Xerox's sales manager Tom Jones's first album Jesus's disciples Aeschylus's finest drama anyone's guess a week's vacation The possessive of a plural noun is formed by adding only an apostrophe when the noun ends in s, and by adding both an apostrophe and s when it ends in a letter other than s. excessive lawyers' fees children's toys the twins' parents the student teachers' supervisor the Smiths' vacation house the boys' baseball team the alumni's fundraising someone with twelve years' experience Exceptions to the general rule Use only an apostrophe for places or names that are singular but have a final word in plural form and ending with an s. Beverly Hills' current mayor the United States' lingering debt problem Cisco Systems' CEO Nouns that end in an s sound take only an apostrophe when they are followed by sake. for goodness' sake for conscience' sake A proper noun that is already in possessive form is left as is. T.G.I. Friday's menu was recently changed. Shared or individual possessives Joint possession is indicated by a single apostrophe. Robert Smith and Rebecca Green's psychology textbook. (they coauthored the book) Stanley and Scarlett's house. (they share the house) Individual possession is indicated by apostrophes for each possessor. France's and Italy's domestic policies are diverging. Chris's and John's houses were designed by the same architect. Avoid awkward possessives Correct but awkward: St. Patrick's Cathedral's Fifth Avenue entrance. Better: The Fifth Avenue entrance for St. Patrick's Cathedral. The apostrophe with other punctuation The apostrophe should never be separated from the word to which it attaches by adjacent punctuation. Correct: The house on the left is the Smiths', but the house at the end of the street is the Whites'. Incorrect: The house on the left is the Smiths,' but the house at the end of the street is the Whites.'

Comma

The comma is the punctuation mark most likely to cause angst. This is largely the result of the many different ways the comma is used. Sometimes, the comma indicates a pause that would occur if the sentence were spoken aloud. Other times, the comma separates grammatical components of the sentence. Finally, there are mechanical and stylistic uses of the comma that are simply conventional. The presence or absence of a comma can change the meaning of a sentence—sometimes dramatically. In extreme cases, an erroneous comma can make a sentence mean the exact opposite of what the writer intended. A careful writer must be a careful user of commas. This entry consists of the following sections: Mechanical uses of the comma There are several uses of the comma that can best be described as mechanical. The use or nonuse of the comma is well established, and writers need only to apply the rules. Numbers Most authorities, including The Associated Press Stylebook and The Chicago Manual of Style, recommend a comma after the first digit of a four-digit number. The exceptions include years, page numbers, and street addresses. We sold 1,270 rare books last year; the most expensive sold for $5,255.50. He lived at 4320 Ocean View Drive until February 5, 2008. Jr. and Inc. The trend with these labels is to omit the comma. David White Jr. is the father of David White III. He was formerly a senior vice president at Apple Inc. Degrees and certifications When a degree or certification is shown after a person's name, it should be set off with commas. The report was prepared by Christopher Smith, PhD. Jane Jones, Esq., has joined the board of directors. Tom Roberts Jr., MD, FACS, will be the keynote speaker at next year's conference. Direct address When directly addressing someone, the person's name or title should be set off with commas. We could not have done it without you, Lisa. Thank you, Governor, for your support. Lori, please stop by my office before you leave for the day. Dates When a date consists of the day of the month followed by the year, the day of the month should be followed by a comma. When the day of the week is provided before the month, the day of the week should be followed by a comma. The store closed its doors for good on Wednesday, October 15, 1958. When the date appears in the middle of a sentence, commas should appear both before and after the year. Her arrival on April 10, 1988, was considered a turning point for the company. When a date is used as an adjective, most authorities require a comma following the year. Yet at least one significant authority (Bryan Garner, in his third edition of Garner's Modern American Usage) omits it. Given the uncertainty, it is best to recast the sentence. Example: The July 10, 2011[,] meeting was canceled due to a hurricane watch. Revised: The meeting scheduled for July 10, 2011, was canceled due to a hurricane watch. No comma is used between the month and the year when they are the only two elements in the date. Correct: The store closed its doors for good in October 1958. Incorrect: The store closed its doors for good in October, 1958. The British style, sometimes used by American writers, reverses the month and date—and eliminates the need for a comma. (See also the essay discussing British and American usage.) Her arrival on 10 April 1988 was considered a turning point for the company. Geographic references Commas should be used to separate geographic elements, as in the examples below. The final geographic element should also be followed by a comma when it appears in the middle of a sentence. The mayor of New York was the first guest to arrive; the mayor of Athens, Georgia, was the last to arrive. His family moved from Bristol, England, to Portsmouth, New Hampshire, when he was eight. The company is headquartered in Sydney, New South Wales, Australia. The listing comma Though not necessarily mechanical, the use of commas in lists is well established. In this usage, the comma separates a series of words, phrases, or independent clauses. Do not place a comma after the last item in the list (see fourth example below) unless the structure of the sentence otherwise requires it (see third example below, in which the comma after audience is required to separate an introductory dependent clause from the main clause). For your entree, you may choose vegetarian pasta, beef, chicken, or salmon. Jane will bring the food, Jose will bring the drinks, John will bring the music, and Jackie will bring the cops. With dignity, grace, and a tremendous empathy for his audience, he delivered the most moving eulogy. I am taking art history, Russian literature, microeconomics, and macroeconomics next semester. Note: The final comma is known as an Oxford comma or serial comma. Some writers omit it, but doing so can cause confusion. In the example immediately above, the serial comma makes it clear that the writer is taking two separate economics courses next semester. Omitting the serial comma makes this unclear. Is it one course covering both microeconomics and macroeconomics, or is it two separate courses? Even though not all sentences will be unclear with the omission of the serial comma, its consistent use is a good habit. (See also the essay on style.) Multiple adjectives that modify or describe the same noun When a noun is modified by more than one adjective, each of which independently modifies the noun, the adjectives should be separated by a comma. In this usage, the comma substitutes for the conjunction and. The wine offered a fragrant, captivating bouquet. (The wine offered a fragrant and captivating bouquet.) It was a long, noisy, nauseating flight. (It was a long and noisy and nauseating flight.) When there are three or more modifying adjectives, it is perfectly acceptable to treat them as a conventional list and include the conjunction and. It was a long, noisy, and nauseating flight. If sequential adjectives do not individually modify a noun, they should not be separated by a comma. He held a bright red balloon. (The balloon is bright red, not bright and red.) When an adjective or adverb is repeated for emphasis, a comma is required. This is a very, very violent movie. Setting off nonrestrictive or nonessential information After lists, the most important function of the comma is to set off nonrestrictive or nonessential information. I will give the document to my brother, Tom. (The writer has only one brother. The brother's name is nonessential and therefore set off with a comma.) I will give the document to my brother Tom. (The writer has more than one brother. In this case, the specific brother—Tom—is essential information and should not be set off with a comma.) Nathaniel Hawthorne's novel The Scarlet Letter has been made into several movies. (Hawthorne wrote more than one novel.) Nathaniel Hawthorne's first novel, Fanshawe, was published anonymously in 1828. (Hawthorne had only one first novel.) As seen in the example above, when the nonrestrictive or nonessential information is found within, rather than at the end of, the sentence, it should be set off with a pair of commas. When the nonessential information comes at the end of the sentence, only one comma is needed. Nonessential explanations When an explanation or definition occurs as an appositive, it should be set off with commas. Mary Smith, a staff writer at the Big City Times, recently wrote a book on that subject. The building's window placement, referred to by architects as fenestration, is among its most distinctive features. That and which These words are frequently misused. That serves as a restrictive pronoun and therefore does not take a comma. John's cars that are leased are never kept clean. (In this case, the dirty cars are specifically those that John leased; John might have non-leased cars that are kept clean.) Which serves as a nonrestrictive pronoun and therefore requires a comma. John's cars, which are leased, are never kept clean. (In this case, all of John's cars are dirty. The fact that those cars are leased is not essential to the meaning of the sentence.) Interrupting elements When a nonessential word or phrase occurs in the middle of a sentence, it should be set off with commas. Your work has been, frankly, awful. The hotel, once we finally found it, was very nice. Introductory matter When a word or phrase occurs at the beginning of a sentence, a comma should usually separate it from the main clause. Yes, we expect to attend the Christmas party. No, you shouldn't respond to a rhetorical question. Honestly, why would you ever think that? To be honest, I didn't enjoy the food. In my opinion, the movie was more compelling than the book. Afterthoughts When a word or phrase follows the main clause at the end of a sentence, it should normally be set off with a comma. I found the painting rather dull, to be honest. You will be joining us for dinner, won't you? Leave some food for me, please. We will not be attending the reception, however. When a sentence ends with an adverb that is essential to the meaning of the sentence, the adverb should not be set off with a comma. We visited Berlin too. We took the train instead. Commas based on sentence structure This is where things get tricky. Mastering the proper use of the comma in these situations is impossible without at least some understanding of grammar. The rules are easiest to learn and deploy if you first understand four common sentence types: compound, simple, complex, and compound-complex. Compound sentences A compound sentence contains two or more independent clauses linked by a coordinating conjunction. Independent clauses are those that can stand alone as complete sentences. The most common coordinating conjunctions are and, but, and or. In certain cases, nor, yet, so, and for act as coordinating conjunctions. Rule: Use a comma before a coordinating conjunction that joins two independent clauses. She purchased the car, but she declined the extended warranty. The prime minister's plan seemed quickly and sloppily put together, and the opposition party immediately attacked it. Are you traveling in first class, or does your employer limit you to business class on international flights? I lost my job, so I can't afford to go to Europe this summer. Exception to the rule: When the independent clauses are closely connected and short, you may omit the comma. Elizabeth flew to the conference and Nancy drove. Simple sentences A simple sentence contains only one independent clause and no dependent clauses. When a simple sentence contains a conjunction, you might be tempted to insert a comma before the conjunction, as you do with a compound sentence. With a simple sentence, however, the general rule is to omit the comma. Rule: Do not use a comma before a coordinating conjunction if the sentence contains only one independent clause. She purchased the car but not the extended warranty. Are you traveling in first class or in business class? Exception to the rule: If omitting the comma leads to confusion or lack of clarity, insert the comma. The alumni's fundraising was better this year than last, and better than expected. Complex sentences A complex sentence contains an independent clause and one or more dependent clauses. A dependent clause, unlike an independent clause, cannot stand on its own as a complete sentence. The conjunctions and prepositions most commonly used to introduce a dependent clause include if, because, while, as, although, since, and unless. Rule: If the dependent clause comes before the independent clause, separate it with a comma. If you can't see without your glasses, you shouldn't be driving. Because of the thunderstorm, our flight has been delayed. Though I don't doubt his sincerity, I cannot agree with his position on that issue. When a sentence begins with two dependent clauses that both apply to the subsequent independent clause, insert only a single comma after the second dependent clause. If you eat a balanced diet and exercise for a few hours each day, you will feel healthier. Rule: If the independent clause comes before the dependent clause, omit the comma. You shouldn't be driving if you can't see without your glasses. Our flight has been delayed because of the thunderstorm. Exception to the rule: If the dependent clause is not essential to the meaning of the sentence, it should be set off with a comma. I cannot agree with his position on that issue, though I don't doubt his sincerity. (Not doubting his sincerity is not the reason I cannot agree with his position; it is merely an additional piece of information.) Rule: If the dependent clause occurs in the middle of a sentence, use commas if it is nonessential; do not use commas if it is essential. The guests, who were all close friends of the president, refused to speak about the events that evening. The guests who arrived more than an hour late were greeted coolly by the host. Compound-complex sentences A compound-complex sentence contains two or more independent clauses and at least one dependent clause. Rule: When a sentence begins with a dependent clause that applies to two independent clauses that follow, insert a comma after the dependent clause, but do not insert a comma between the independent clauses. If we want this business to work, you need to find suppliers and I need to find buyers. Rule: When a dependent clause occurs between two independent clauses and applies only to the second, the dependent clause should be set off with commas. The prime minister's plan seemed quickly and sloppily put together, and when they saw it, the opposition party immediately attacked it. When comma rules conflict When you diligently apply the rules described above, you sometimes end up with a sentence nearly bursting with commas. For example: I originally wanted to be a rock star, but I decided to become an investment banker. This is a compound sentence (i.e., one with two independent clauses joined by the conjunction but), the rule for which is to insert a comma before the conjunction. If you want to add a nonessential comment before the second clause, you end up with this: I originally wanted to be a rock star, but, in the end, I decided to become an investment banker. This sentence appears to follow the rules described above. There is a comma before the conjunction (but), and the nonessential comment (in the end) is set off with a pair of commas. There was a time when this sentence would be punctuated exactly this way. Today, such a sentence is considered over-punctuated. There are two schools of thought on how best to lighten the punctuation of such a sentence. The traditional approach, advocated by William Strunk Jr. in The Elements of Style, removes the comma after the conjunction. Thus: I originally wanted to be a rock star, but in the end, I decided to become an investment banker. With this approach, the commas reflect the natural pausing points if the sentence were to be read aloud. Yet some writers object to this. They argue that whatever is inside a pair of commas should be capable of being removed without turning the sentence into nonsense. In this case, applying that test results in this: I originally wanted to be a rock star I decided to become an investment banker. That sentence does not make sense. The contemporary school of thought instead removes the comma before the conjunction: I originally wanted to be a rock star but, in the end, I decided to become an investment banker. Now when you remove the comma-bracketed material you get: I originally wanted to be a rock star but I decided to become an investment banker. The resulting sentence makes sense. But it's missing the comma that is ordinarily required before the conjunction linking two independent clauses. What's the solution? There are at least two possibilities. The nonessential in the end comment doesn't really need to be bracketed by commas; the meaning is clear enough without them. I originally wanted to be a rock star, but in the end I decided to become an investment banker. The other approach is to introduce a semicolon. This eliminates the troubling conjunction (but). I originally wanted to be a rock star; in the end, I decided to become an investment banker.

Em dash

The em dash is perhaps the most versatile punctuation mark. Depending on the context, the em dash can take the place of commas, parentheses, or colons—in each case to slightly different effect. Notwithstanding its versatility, the em dash is best limited to two appearances per sentence. Otherwise, confusion rather than clarity is likely to result. Do not mistake the em dash (—) for the slightly narrower en dash (-) or the even narrower hyphen (-). Those marks serve different purposes and are further explained in other sections. Em dashes in place of commas A pair of em dashes can be used in place of commas to enhance readability. Note, however, that dashes are always more emphatic than commas. And yet, when the car was finally delivered—nearly three months after it was ordered—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell. Em dashes in place of parentheses A pair of em dashes can replace a pair of parentheses. Dashes are considered less formal than parentheses; they are also more intrusive. If you want to draw attention to the parenthetical content, use dashes. If you want to include the parenthetical content more subtly, use parentheses. Note that when dashes are used in place of parentheses, surrounding punctuation should be omitted. Compare the following examples. Upon discovering the errors (all 124 of them), the publisher immediately recalled the books. Upon discovering the errors—all 124 of them—the publisher immediately recalled the books. When used in place of parentheses at the end of a sentence, only a single dash is used. After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction). After three weeks on set, the cast was fed up with his direction—or, rather, lack of direction. The em dash in place of a colon The em dash can be used in place of a colon when you want to emphasize the conclusion of your sentence. The dash is less formal than the colon. After months of deliberation, the jurors reached a unanimous verdict—guilty. The white sand, the warm water, the sparkling sun—this is what brought them to Hawaii. Multiple em dashes Two em dashes can be used to indicate missing portions of a word, whether unknown or intentionally omitted. Mr. J—— testified that the defendant yelled, "Die, a——," before pulling the trigger. From the faded and water-damaged note, we made out only this: "Was ne——y going to m—— K——, but now ——t." When an entire word is missing, either two or three em dashes can be used. Whichever length you choose, use it consistently throughout your document. Surrounding punctuation should be placed as usual. The juvenile defendant, ———, was arraigned yesterday. Spaces with the em dash The em dash is typically used without spaces on either side, and that is the style used in this guide. Most newspapers, however, set the em dash off with a single space on each side. Most newspapers — and all that follow AP style — insert a space before and after the em dash. Producing the em dash Many modern word processors will automatically insert an em dash when you type a pair of hyphens. Otherwise, look for an "insert symbol" command. If you are using a typewriter, a pair of hyphens is the closest you can get to an em dash.

Semicolon

The semicolon is sometimes described as stronger than a comma but weaker than a period. In certain uses, this is a reasonably accurate definition. Yet there is more to the semicolon than that. Between independent clauses when a coordinating conjunction is omitted Most commonly, the semicolon is used between two independent clauses (i.e., clauses that could stand alone as separate sentences) when a coordinating conjunction (for, and, nor, but, or, yet, so) is omitted. The upperclassmen are permitted off-campus lunch; the underclassmen must remain on campus. The example above could be recast with the conjunction but, in which case a comma, rather than a semicolon, would be required. The upperclassmen are permitted off-campus lunch, but the underclassmen must remain on campus. Technically, the semicolon could be replaced with a period, since each independent clause is a complete sentence. The semicolon, however, emphasizes the connection between the two clauses. Note: When the second clause expands on or explains the first, the colon is the better mark. Between independent clauses linked by a transitional expression The semicolon is also used between two independent clauses linked by a transitional expression (e.g., accordingly, consequently, for example, nevertheless, so, thus). Heavy snow continues to fall at the airport; consequently, all flights have been grounded. Hyperinflation makes it extremely difficult to keep track of prices; thus a quart of milk might cost $10 in the morning and $200 in the afternoon. In lists with internal commas The semicolon can also be used in lists with internal commas. In this usage, the semicolon acts as a sort of super-comma. The new store will have groceries on the lower level; luggage, housewares, and electronics on the ground floor; men's and women's clothing on the second floor; and books, music, and stationery on the third floor. In elliptical constructions When combined with a comma, the semicolon can be used in elliptical constructions. In this case, the comma serves as an ellipsis, eliminating the need to repeat an understood portion of the initial clause. In 1992, Starbucks had under 200 stores; ten years later, over 5,000. Some people brought food; others, clothing; yet others, merely a willingness to help.