I’ve been wondering for some time whether punctuation marks like full stops, commas and question marks should go inside or outside a closing quotation mark, and getting more and more confused. But now I’ve realised that there’s a reason why I’m so confused. Although both British English and American English follow the same rules up to a point, when it comes to commas and full stops they diverge.

In British English, full stops, commas, question marks, exclamation marks, colons and semi-colons that are part of the quotation are placed inside the quotation marks, but if they are not part of the quoted words they are placed outside.

In British English, we would write:

He said, ‘I think the weather will be good tomorrow.’*

He said that he thought the weather would ‘be good tomorrow’.

My favourite song is ‘Autumn Leaves’.

‘Hello, everyone’, she said.

She asked, ‘Have you ever been to London?’*

Have you ever read ‘Strangers on a Train’? 

In American English, the same rules apply but with the exception that full stops and commas are always placed inside quotation marks:

My favourite song is ‘Autumn Leaves.’

‘Hello, everyone,’ she said.

*Notice that in these two examples, an additional full stop after the quotation mark to end the sentence is not considered necessary.