The Editor's Manual
Free learning resource on English grammar, punctuation, usage, and style.
Both styles are correct: “President’s Day” (possessive, with the apostrophe) and “Presidents Day” (descriptive, without the apostrophe).
Place an apostrophe before “s” in Mother’s Day and Father’s Day. Also capitalize the two words that make up the name of the holiday.
“One in” followed by a number (e.g., “one in five”) is grammatically singular. However, such phrases refer not to one person or thing but to a proportion, and the use of plural verbs is acceptable, although singular verbs are preferred in formal usage.
Place quotation marks around direct speech or a quotation. Quotes may also enclose a word or a phrase used ironically or as itself. Quotation marks set off titles of shorter works (like a chapter, article, or poem).
Smart (or curly) quotes are paired quotation marks that curve toward the text they enclose, indicating clearly whether they start or end a quote. Straight quotes are nondirectional.
Both “who” and “that” can refer to people. “Who” is preferred in formal usage.
Round brackets are called “parentheses” in American English but referred to simply as “brackets” in British English. In American writing, square brackets are used within parentheses, while the British use round within round brackets (nested parentheses).
Use commas to integrate closely related information into the flow of the sentence. Use parentheses to set off supplementary information or an afterthought from surrounding text. Use dashes to be emphatic or dramatic and make additional information or an aside stand out.
Place punctuation inside parentheses if it belongs to the parenthetical text, and outside if it belongs to the larger sentence. Periods, question marks, exclamation points, and quotation marks go inside if they are meant to punctuate the parenthetical text, while commas, dashes, colons, and semicolons always appear after a closing parenthesis.
Place a period within parentheses if the entire sentence is contained in the parentheses. Place the period outside if the parenthetical phrase appears within a larger sentence.