The Editor’s Manual
Free learning resource on English grammar, punctuation, usage, and style.
Commas, colons, semicolons, dashes, and other punctuation marks that make you tear your hair out.
Use a colon to introduce a list or a quotation, or to explain and amplify a statement. It directs the reader’s attention to the information that follows. It can also serve as a sign or separator.
Use an apostrophe with possessive nouns (New Year’s Day, Mother’s Day, Presidents’ Day) but not with descriptive terms (Christmas Eve, Human Rights Day).
“It’s” (with the apostrophe) is a contraction of “it is” or “it has.” “Its” (without the apostrophe) is the possessive form of “it.”
The serial comma is used before the conjunction (“and,” “or”) that marks the final item in a series. Using it is optional, but it can sometimes affect the meaning of a sentence.
“Who’s” is the contraction of “who is” or “who has,” while “whose” is the possessive form of “who.”
An ellipsis is a series of three dots. In a quotation, an ellipsis signifies omitted words. In a dialogue or narrative, the ellipsis shows faltering speech or a pause.
A period indicates a longer pause than a comma or a semicolon. Use a period to end a sentence and to mark the end of a thought or fragment. Also use periods in abbreviations and to separate initials before a surname.
Use commas to make lists, set off phrases, separate clauses, and indicate that a detail is nonessential in a sentence.
Avoid using an apostrophe before the “s” in a plural, unless not using one would result in confusion (e.g., two “i’s” in “iridescent”).
Use a comma between the items in a list, to separate two independent clauses, and after a subordinate clause. Enclose nonessential phrases and clauses in commas.