one for the grammar nazis

In summary, when punctuating quotations, US English places most punctuation inside the closing quotation mark.
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Users of British English place the comma in the following sentence outside the quotation marks.

"Hello", said John.

Incidentally, the comma is used to separate *what* was said from *who* said it. Here's another example:

"Hello", he said. "How are you today?"

Note that even though the comma is outside the quotes, the question mark is inside the quotes. Why?

The comma is not considered to be part of what was actually said, so it was placed outside the quotes. (It's part of the punctuation of the surrounding sentence, rather than of the quotation.) The question mark, however, is part of the spoken text, so it's placed inside the quotes.

There is a certain common sense to this, but it does make punctuating British English harder than punctuating US English.

http://www.translationdirectory.com/article791.htm