The Editor’s Manual
Free learning resource on English grammar, punctuation, usage, and style.
Commas and periods always go inside quotes in US style. In UK style, they go inside only if they apply to the quoted text. In all styles, question marks and exclamation points go inside only if they apply to the quoted text.
Periods always go inside quotation marks in American usage. In British usage, a period (or full stop) goes inside only if the quotation is a complete sentence.
Commas always go inside quotation marks in American style. In British style, commas go inside or outside depending on whether they punctuate the text within quotes or the surrounding sentence.
Use single inside double quotation marks to show a quote within a quote in US style. In British style, use double inside single quotes.
US style is double quotes with single quotes reserved for quotes within quotes. British is single quotes with double quotes used for quotes within quotes. Commas and periods always go inside quotation marks in US style but not in British.
Double quotes enclose text in US style, with single quotes used only for quotes within quotes. Single quotes are the default in British style, with double quotes reserved for quotes within quotes.
The abbreviation for United States may be written with or without internal periods: U.S. or US. Both styles are acceptable.
Use “Sincerely,” “Best wishes,” or “Regards” (or “Warm regards,” “Best regards,” “Kind regards”) to close a formal or business email. Don’t use casual sign-offs like “Cheers” or “Best” in formal communication.
Use either a comma or a colon after a greeting. The colon is preferred in business or other formal communication in U.S. style.
Various phrases can begin an email, depending on formality (dear So-and-So, hi, hello, good morning). Using an appropriate salutation can set the right tone for your correspondence.