In American English, quotation marks are always placed inside any adjacent punctuation marks, except for colons and semicolons, which are always placed outside the quotation marks.

In the US, commas and periods always go inside the quotation marks. In the UK, the tendency is to place them outside, unless they appear in the original quotation, in which case they go inside.

In American (and often Canadian) usage, commas and periods always go inside quotation marks, but other punctuation marks, such as question marks and exclamation points, go inside only if they apply to the quoted text.

US and UK English also differ on where to place punctuation within quotation marks. In US English, commas and periods that follow a quote are placed within the quotation marks. In UK English, all punctuation marks are placed outside the quotation marks, except when they are part of the original quotation.

In American English, periods are always placed inside the quotation marks, even if they are not part of the original quote.