ABSTRACT
In modern usage, there is still variation; but it is possible to generalise by saying that the most common usage in British English (advocated by New Hart’s Rules [p85] and by Copy-Editing: the Cambridge Handbook [p264]) is to use single as the norm, and to use double only when you want to include a quotation or an emphasised word within a quotation. The most common practice in American English usage (advocated by The Chicago Manual of Style [p453] and by MerriamWebster’s Manual for Writers and Editors [p31]) is to use double as the norm, and to use single for quotations or emphasised words within quotations.
