Quotations and Dialogue

Q. Can you distinguish when a single quotation mark is used versus a double quotation mark? I’m not referring to quotes within quotes, but about the use of single quotation marks closer to linguistic uses. I see both single and double quotation marks in instances seemingly for special meaning but not limited to linguistics. (That also seemingly will drive whether a comma is placed inside or outside the closing single quotation mark.)

A. For nonspecialist texts, Chicago recommends double quotation marks for everything except quotations within quotations. The comma or period goes inside.