Hyphen — Hyphenate compound adjectives only if required for clarity: “fastest-growing company”; “high-level discussion.” Don’t use hyphens with commonly understood terms, adverbs that end in ly and between figures and units of measure: “greatly exaggerated claims”; “2 percent rule.” Do not use a hyphen with a compound modifier after the noun: “The driver was well paid.”
Dash — Dashes set off a series within a phrase: “Of the many breakfast options — omelets, waffles, pastries — he only wanted coffee”; indicate a break in thought: “Felipe’s is a popular eatery — in Harvard Square”; or attribute a quotation to an author: “‘You must do the thing you think you cannot do.’ — Eleanor Roosevelt.” When using text editors that don’t support dashes, use two hyphens for each dash.
Comma — Use a comma to set off a person’s town of residence, age and other such information: “Tom Menino, Boston, was a popular speaker”; “Jean Dupont, 32, was released yesterday.” See Oxford Comma entry for OCU’s preferred style.
Period — Use only one space after the end of a sentence. Period.
Colon — Capitalize the first word after a colon only if it’s followed by a complete sentence. Colons go outside quotes unless they’re part of the quoted material.
Apostrophe — An apostrophe indicates possession. Add an ‘s to all single nouns and names, even if they already end in an s: “My boss’s vacation begins tomorrow.” For singular proper names ending in s, use only an apostrophe: “Kansas’ crisis.” For plurals of a single letter, add an apostrophe and an s: “Mind your p’s and q’s,” “the Oakland A’s.” Do not use apostrophes for decades or acronyms: the 1990s, CDs.
Quotation marks — Periods and commas go inside quote marks: “‘Reginald, your hairstyle makes me nervous,’ she said.” The position of dashes, semicolons, exclamation and question marks depends on what’s being questioned or exclaimed: “Was she right to say, ‘Your shoes are a joke’?”
Parentheses — AP style suggests avoiding parentheses when possible, and instead rewriting text or using dashes or commas to set off the information. If parentheses are required the rules are: If the parenthetical is a complete, independent sentence, place the period inside the parentheses; if not, the period goes outside.
