Quotation marks

Put double quotation marks (“) around speech  and titles of books, reports, etc. For quotes within speech, use single quotation marks (‘).

This is the convention for newspapers and magazines. As we follow The Economist’s lead on most style points, this is the convention to use for most publications. If you are working on a book, then the rule is reversed, with single quote marks used for speech etc, and double ones for quotes within speech.