Punctuation Guide

A quick reference for English punctuation — commas, semicolons, colons, apostrophes, quotation marks, dashes, and end marks — with examples.

Comma ( , )

The most overused and underused mark in English — it separates, but doesn't always mean 'pause'.

Separates items in a list: I bought apples, oranges, and bananas.
Goes before a coordinating conjunction (and, but, or, so) joining two complete sentences: She was tired, but she kept working.
Follows an introductory word or phrase: However, we decided to stay. After the meeting, we went home.
Surrounds non-essential information that could be removed without changing the core meaning: My brother, who lives in Paris, is visiting. (compare: The brother who lives in Paris is visiting — no commas, because which brother matters here.)
The comma before and/or in a list (apples, oranges, and bananas) is called the Oxford comma — optional in British English, more standard in American English, and genuinely useful for avoiding ambiguity.

Stronger than a comma, weaker than a full stop — for joining ideas that are closely related.

Joins two complete, closely related sentences without a conjunction: I have a big test tomorrow; I can't go out tonight.
Separates items in a list when the items themselves already contain commas: We visited Paris, France; Rome, Italy; and Berlin, Germany.

Announces something — a list, an explanation, or a quotation — after a complete sentence.

Introduces a list: You'll need three things: eggs, flour, and sugar.
Introduces an explanation or elaboration: There was one problem: nobody had the keys.
Introduces a quotation: She said it best: "Nothing worth having comes easy."
The words before the colon should form a complete sentence on their own — not The ingredients are: eggs, flour, sugar, which is a common mistake.

Only ever means possession or a missing letter — never a plain plural.

Shows possession: the dog's bone (one dog), the dogs' bones (more than one dog).
Forms contractions, standing in for missing letters: it's (it is), don't (do not), they're (they are).
Never used to make a regular plural — apples, not apple's.
its (possessive) vs it's ('it is'/'it has') is the single most common apostrophe mistake — see the confused words page.

Enclose someone else's exact words — and British and American English disagree on where the punctuation goes.

Enclose direct speech: She said, "I'll be there at six."
Enclose titles of short works — articles, poems, songs; longer works (books, films) are usually italicized instead.
American English puts commas and periods inside the closing quotation mark: She said, "I'm ready." British English often puts them outside unless they're part of the quoted material: She said, "I'm ready".

Three different marks, three different jobs, despite looking similar.

Hyphen (-): joins compound words or compound modifiers before a noun: mother-in-law, a well-known author.
En dash (–): shows a range: pages 10–20, 2020–2024.
Em dash (—): marks a parenthetical break or abrupt shift — like this — often replacing commas or parentheses for emphasis.

End marks that carry meaning, not just punctuation-by-habit.

Question mark ends a direct question: What time is it?
Not used after an indirect/reported question: She asked what time it was — no question mark, because it's now a statement.
Exclamation mark shows strong emotion or emphasis — used sparingly in formal writing, since overuse weakens its effect.

Not just 'the first word' — English capitalizes a specific, learnable set of things.

The first word of every sentence: The train was late.
The pronoun I, always, wherever it falls in a sentence: My sister and I were there.
Proper nouns — specific people, places, organizations, and brands: Maria, Tokyo, the United Nations, Microsoft — but not the common noun they belong to: a city, her sister, a company.
Days of the week, months, and holidays: Monday, March, Thanksgiving — but not seasons: summer, winter.
Nationalities, languages, and other adjectives formed from proper nouns: French cheese, a Shakespearean play, Chinese New Year.
The first word — and usually every 'important' word (not a, the, and, of) — in titles of books, films, and articles: The Lord of the Rings, A Tale of Two Cities.
The first word of a direct quotation, if it's a full sentence: She said, "Nothing worth having comes easy." — but not when the quotation continues a sentence: She said the plan was "too risky to attempt."
Job titles are capitalized before a name (President Biden) but usually lowercase when used generally (the president spoke) — a common source of over-capitalization.