An Apostrophe is the mark of punctuation (') used (1) to indicate a missing letter or letters, as in contractions such as isn't, they're, and it's, (2) to distinguish genitives of nouns from noun plurals not in the genitive (boy's, boys', but plural boys), and (3) sometimes to mark plural numbers and letters (three 6's, two A's). Never use an apostrophe in front of the -s ending that forms a plural noun (The sign says Fine Meal's), in front of the -s that forms a third-person singular present tense verb (Accused Plead's Insanity), or before the -s in an absolute possessive pronoun (This hat is her's).

Brackets ([ ]), also called square brackets, are marks of punctuation that have three main purposes. (1) In quotations they distinguish material added to a quotation, such as disclaimers of responsibility for a misspelling in the original text ("it was a separate [sic] meeting") or to further explain quoted matter (He said, "I read my favorite novel [War and Peace] every year"). (2) Brackets also serve as parentheses within parentheses in text (or as parentheses around parentheses in complex mathematical equations). (3) Conventionally, square brackets set off phonetic symbols (Phone begins with an [f] sound). Angle brackets (< >) are sometimes used for these same purposes, but much less often.

This punctuation mark, the colon, (:) can (1) signal a forthcoming list, as in He sold sundries: needles, thread, pins, buttons, and thimbles; (2) introduce a further amplification or a summary of what has just been said, as in After years of work, he finally had it: the championship; (3) let one clause explain another, as in He was late: his car had broken down; (4) lead into a long quotation, as in Jefferson wrote: When in the course of human events,…; and (5) do such separating tasks as these: Henry IV, Pt. I, II:iv:122; Dear Sir:; New York: Longman, 1987; and 11:15 A.M.

The comma (,) usually separates one element of a locution from another without actually setting them completely apart. It separates independent clauses joined by coordinating conjunctions such as and (He ordered them, and he paid for them) and sets off nonrestrictive modifiers, appositives, and other parenthetical elements (Fred, who teaches Spanish, is being promoted; George Smith, my uncle, has died; His humor is, I think, bizarre). The comma also separates sentence adverbs and adverbial clauses and phrases from the main clause they precede, and if the adverbial clause interrupts the main clause, commas surround it (Furthermore, I don't believe that she's guilty; I don't believe, furthermore, that she's guilty). Commas separate words in series (a horse, a dog, and a cow; note that American English prefers and many editors require the comma after dog, but the British rarely use it, and some Americans don't use it either) and in a string of adjectives modifying a noun (a dark, windy, unpleasant day). The comma can introduce, enclose, and end direct quotations (I said, "Go home"; I said, "Go home," and I threw him out; "Go home," I said). It also separates contradictory locutions (It's green, not blue), sets off direct address (Yes, Fred, I'll be there), and marks off certain rhetorical questions (He's a fool, isn't he?). And the comma can make clear that a word or words have been omitted in an otherwise repetitive locution, as in Some like it hot; others, cold, and serves to prevent ambiguity, as in For John, Henry was a model.

The comma also performs a range of stylistic chores which sometimes differ slightly from publisher to publisher and stylebook to stylebook. It may separate date and year (July 4, 1776), city from state (Chicago, Illinois), day from date (Monday, April 10), a name from a title in apposition (David Hankins, Building Monitor), and the last name from the first, when they are presented in reverse order (O'Hara, James D.). In each of these cases, a comma may (and sometimes must) follow the second element as well. Commas also mark the thousands in a long number ($10,000,000) and often signal the end of salutation and complimentary close in personal letters (Dear Milton, Love, Harriet).

The dash (—) is a mark of punctuation similar to but physically longer than a hyphen and used for other purposes. Typed, a dash is usually rendered with two hyphens; in printed matter. It signals an interruption in syntax and in the idea of a sentence: When the governor understood how—did you hear the phone? It also can be used as a colon might be used, to introduce a summarizing phrase following a list of details: We had studied math, English, chemistry, philosophy, history—the whole liberal arts curriculum. It can replace commas or parentheses that enclose grammatically parenthetical clauses or phrases: They took every precaution—it seemed to take forever—to ensure our safe arrival. It can also be used to set off an interjected question or exclamation: The need now—urgent, is it not?—is for more funding. The dash also appears in attributions of quotations: Water, water, every where, nor any drop to drink. —Coleridge. Finally, the dash is frequently used in Informal writing—especially in personal letters—to suggest the spontaneity, breeziness, and relaxed structure we usually find in conversation. It can be effective when so used, but its overuse to avoid other punctuation and to evade the requirements of more conventional syntax can be trying for the reader, even in a personal letter. In more Formal writing overuse can suggest that the writer is hasty, careless, and imprecise.

This punctuation mark, the double hyphen (=) is called for in some stylebooks to separate parts of a word at the end of a line and the beginning of the next when the word would ordinarily already be hyphenated at that point anyway; if the break came at the hyphen in high-energy, for example, the line would end high=, and the next line would begin energy.

The ellipsis is the use of periods or other marks to indicate the omission of words in a quotation: "Better late than never, but…." Conventionally, use three periods within a sentence. When your ellipsis ends with the end of a phrase, clause, or sentence in the original, use four periods or three plus whatever mark ended the original.

The exclamation point (!) is the punctuation mark used to give the sort of emphasis to a word, phrase, or sentence that suggests loud, vigorous, forthright delivery. Never! Free at last! Never darken my door again! In English it always goes at the end of the locution to be emphasized. But stridency is seldom approved in speech, and so in writing too be sparing of the exclamation point. Rely on your words, not your punctuation, to make your passion ring forth.

The hyphen (-) English uses to link the parts of some compound words (drug-dependent, blow-dry), including most of those containing prepositions (mother-in-law, top-of-the-line); to combine single-word proper nouns such as place names (the London-Paris flight, although in printed matter the New York–London flight and the Saint-Lambert–Montreal route, will look slightly different, because printing uses the en dash to form compounds when one or both of the words are made up of two words or are already hyphenated); to put between some prefixes and the root words to which they're joined (non-Christian, self-destruct, pre-Columbian); to avoid ambiguity in compound modifiers (blue-green enamel, a slow-moving van, but a slowly moving van, because -ly adverbs and the adjectives they modify are not hyphenated); to use between parts of fractions as these are spelled out, especially as modifiers (a three-fourths majority); to mean "up to and including" when used between numbers or dates (50–59, 1922–1930, although here Edited English requires en dashes); to divide elements of compound two-digit numbers over twenty (twenty-one, ninety-nine). Note that even if you use a hyphen between parts of an adjective or adverb (an eighteenth-century statesman), you should not do so in a modifier plus a noun (She lived in the eighteenth century).
 The hyphen's other main use is to link the parts of a word divided for lack of space at the end of a line of writing; in this use the hyphen appears at the end of the last syllable for which there is room on that line, with the rest of the word then appearing at the beginning of the next line. Good desk dictionaries show you where words may conventionally be divided, usually with a dot or space between syllables where a hyphen may go. Generally editors try to avoid hyphenating any word at the end of a line when the word already has a hyphen in it.

Parenthesis are the punctuation marks we use to set off explanatory or other additional material not needed in the main sentence. Stylistically, parentheses are a way of setting off an aside in a syntactic structure. Paired dashes can do this too—they're the most vigorous of such marks—and parentheses are a bit stronger than paired commas for a similar purpose. Conventionally parentheses are also used to set off numbers, as in (1), (2), etc.; to repeat and confirm a number or give an abbreviation in a text, as in There were fifteen hundred three (1,503) applicants and The agency was the United Nations Relief and Rehabilitation Agency (UNRRA); and to indicate alternative possibilities, as in forms to be filled out: Fill in name(s) of occupant(s) of this address.

Conventional combinations of parentheses and other marks of punctuation are these: a full sentence within parentheses but not within another sentence begins with a capital letter and ends with a period or other terminal mark, all placed within the parentheses; inside a sentence, the materials within parentheses need not be capitalized nor have end punctuation within them but may include a question mark or an exclamation point; abbreviations within parentheses may end with a period; within a sentence, punctuation will go not immediately before a parenthetical insertion but directly after the final parenthesis mark, as in He gave his name (grudgingly), but he refused to give his address; and a parenthetical remark within parentheses will be surrounded by square brackets, not by a second set of parentheses (in mathematical expressions, the reverse is true: material already containing parentheses will be enclosed by square brackets, which in turn may be enclosed by braces)

This period (.) is used to indicate the ends of sentences or sentence fragments that do not use question marks or exclamation points. Conventionally it occurs at the ends of some abbreviations, after numbers and letters that indicate the items in lists of outlines, and after initials in a person's name; in some stylebooks, periods are specified as the punctuation in act, scene, and line references (II.iii.45–48) and the like.

This question mark (?) appears at the end of sentences that are questions. In direct quotations, the question mark falls inside the final quotation mark; "Where?" she asked. In indirect quotations, no question mark is used: She asked where he had been. We also use question marks to indicate that we are unsure of a fact or opinion: The life dates of Ethelred II (the Unready) were 968?–1016.

Quotation marks come in two forms, double and single. The double quotation marks (opening " and closing ") are used to enclose the words of a direct quotation: She said, "I'll never see you again." (They are never used in indirect quotation: She said she'd never see him again.) They are also used to enclose words or phrases quoted from others or words that may be slang or that are in some other way being used peculiarly: The speaker tried to put a favorable "spin" on his denial. The "pacification plan" was in fact simply a euphemism for a bloody conquest. But be sparing: most editors discourage the use of such quotation marks for effect rather than for a substantive reason, and overuse of these marks in any writing is affected.

Convention also calls for double quotation marks around the titles of short stories, short poems, short musical compositions, and the names of plays, chapters in books, and radio and television programs: Frost's "The Road Not Taken," "Eye Witness News." (Titles of longer works usually require italics instead, and sometimes the decision is arbitrary or simply conventional: books of the Bible, for example, are almost always italicized rather than placed in quotation marks, and the same is true of the titles of Shakespeare's plays.)

A key problem with quotation marks is which other marks of punctuation go inside the closing quotation mark(s) and which belong outside. In the United States, most stylebooks and most editors follow these rules: periods and commas belong inside, colons and semicolons outside. Other marks—question mark, dash, and exclamation point, for example—go inside when they belong with the quoted material, outside when they belong to the main sentence.

When quoting a long passage of two or more paragraphs, the usual procedure in written American English is to use no quotation marks and instead to set off the entire passage of quoted matter by indenting it. If you decide to use quotation marks instead, however, the usual procedure is to begin each paragraph of the long quotation with quotation marks but to use a closing quotation mark only at the end of the final sentence in the quoted passage. In any event, use only one of these methods with any given quotation.

In American writing single quotation marks are restricted mainly to enclosing a quotation within a quotation: The dealer said, "I'm sorry, I thought you said ‘I pass.'" Note that a period goes inside both final quotation marks when the two quotations end together.

The semicolon (;) has two important uses in written English. (1) It coordinates (separates yet connects evenhandedly) two independent clauses not joined by a coordinating conjunction: I ran to the door; no one was there. Notice particularly its use when independent clauses are joined by conjunctive adverbs such as however and furthermore. These are not coordinating conjunctions, and therefore a comma is not enough punctuation; a semicolon does the job: We were there early; nonetheless, they had already left. With a coordinating conjunction such as and or but, a comma would serve: We arrived early, but they had already left. (2) The semicolon also serves to separate clauses or phrases in series constructions when these already contain commas (He had a tall, black horse; a wagon, which someone had given him after the battle; and a threadbare, tattered carpetbag) and elsewhere where there are already other commas.

Another point about the semicolon: the convention is that the semicolon always belongs outside the final quotation marks: He said, "I hit him"; he smiled wickedly.

A virgule (also called a diagonal, slash, slash mark, or solidus) is a slanted line (/) used between two words to suggest that they are alternatives (and/or), between the parts of a fraction (1/2), or for other typographical purposes, such as indicating line endings when verse is quoted without indentation, within a regular prose paragraph. Slanted in the other direction (\), these marks are sometimes used to enclose phonemes, and in computer applications, where they are called back slashes or backslashes, they are used in certain commands.