The Editor's Manual
Grammar, usage, punctuation, and style resource for editors, writers, and learners of the English language.
Don’t capitalize a word after a colon within a sentence, or a single sentence after a colon. Capitalize a question or a series of two or more sentences introduced by a colon. Also capitalize subtitles.
Capitalize specific time periods (Middle Ages), but lowercase descriptive terms (medieval times). Also capitalize proper names (Victorian era) and geological time periods (the Jurassic).
Avoid capitalizing corporate job titles when used descriptively or as common nouns. Capitalize them when used as part of a name or to address a person.
Capitalize words like “professor” and “principal” as titles before a name, but not when used descriptively after a name or as common nouns.
Capitalize words like “queen,” “prince,” “duke,” and “duchess” when used in titles or before a name (“Queen Elizabeth II and Prince Philip, Duke of Edinburgh”). References to a specific person may also be capitalized (“the Queen”).
Words like “pope,” “bishop,” “rabbi,” “reverend,” and “father” are capitalized as religious titles before a name but lowercased as common nouns.
Capitalize kinship titles (mom, dad, uncle, grandma, etc.) when using them as names (“Hi, Mom”), but lowercase them as common nouns (“your mom”).
Capitalize military ranks like “general” and “captain” when used as titles before a name or to address a person. Lowercase them as common nouns.
Capitalize words like “president” when used as titles before a name or to address someone (“President Biden,” “Yes, Prime Minister”). Otherwise, lowercase them (“the new president,” “our prime minister”).
The abbreviations “a.m.” and “p.m.” are generally lowercased in running text, though they may also be capitalized. When lowercased, the letters are followed by periods; when capitalized, periods are omitted.