My mother tongue is Chinese, and as I read English articles, I find a convention in written English that I can't explain.

If a quoted word appears at end of a sentence, the period is written inside the quote instead of being written outside, which is quite counter-intuitive to me.

For example, a paragraph from Samsung SSD White Paper.

period inside quotes, sample sentence

Notice it is written as:

... called a "strobe."

instead of

... called a "strobe".

Can someone help explain this?


The explanation for putting the period/full stop inside the quotation marks goes back to the early days of printing in Europe, back in the 1500s.

Each character in a printed line of text - letter, number, punctuation mark - came from a separate piece of metal type. All the individual pieces of metal were lined up on a template for printing (like this). The pieces of metal for each character were different sizes, depending on the character on the metal. An "m" was wider than an "i", for example. And, a full stop / period (.) was on a very small piece of metal.

When the punctuation was done as usual, the full stop / period was placed at the end of the line of type, after the quotation mark character. However, in this position at the end, the small piece of metal carrying the full stop would often fall off or even break. Therefore, printers starting putting the full stop before the final quotation mark, to stop it falling off or breaking.

This practice was in place well before 1600, when the first English colonists set out for the American continent.

The English in America and the English in Britain both put the period inside the final quotation mark for the next few hundred years. However, sometime during the 1800s and 1900s, when typesetting was done more on large machines and then computers, the British people went back to putting the full stop outside the final quote. The Americans did not change back.

Therefore, modern British English has the full stop outside the final quotation mark (the "logical quote") while modern American English has the period inside the final quotation mark (the "typesetters' quote").

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    Thank you for pointing out the (possible) historical reason behind the scene. However, I'm starting to wonder about two things. First, why didn't the pre-1600s people make the . metal-piece as wide as A, so that it was not easily broken. Second, it is still weird they came up with the idea of putting . inside " without worrying about other sentences(95% or more) having fragile . metal-pieces at the end.
    – Jimm Chen
    Feb 10 '14 at 8:13
  • Type-makers didn't make the "." piece as wide as an "A" for two reasons. One, because this would cause strange spacing in the letters in the final printed text (look up "kerning"). Two, because it was a waste of metal to make a piece of type wider than it needed to be (metal cost money!). Feb 10 '14 at 12:40
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    Strange spacing? I can't understand. Most people including you and me, when typing English on a computer, habitually add a space after the period so that it looks nicer than without a space, right?
    – Jimm Chen
    Feb 11 '14 at 5:04
  • But a period/full stop isn't used only at the end of a sentence. What about ellipses (...) and decimal points (2.5)? And... why are you challenging what people did 400 years ago? They did what they did for their own reasons, whether it makes sense to you or not. Feb 11 '14 at 12:29
  • OK. Considering ellipses and decimal points, I confess it is necessary to keep a thin period metal-piece. But one thing still shrouded is that how do they cope with the 95% cases that sentences end with a sole period.
    – Jimm Chen
    Feb 13 '14 at 2:46

The "answer" is that, unfortunately, this is one of American English's many "rules" without a logical explanation. As you state, it would typically be more logical (and proper in Canada, Australia, and the UK as far as I know) to place the punctuation with the words it was meant to accompany. In your example, the quotes "belong with" the word strobe and probably shouldn't be broken by the placement of a period or comma between the word and the punctuation.

Regardless, it's a fairly accepted rule. APA, MLA, and Chicago styles all agree that they should be placed within the quotes.

Onto the why...

I've heard it said that the convention arose in the days of typewriters and hand-set printing, where placement of periods and commas outside of quotations were liable to result in broken keys, misplacement of characters, or other nuisances. Here's a footnote from a fairly. respectable source citing this as the mythology behind the convention. A copyrighter at work says that the practice started in the '60s as a matter of cosmetics; they felt it looked better. As I'm not that old, I can't vouch for this explanation. I've never heard a better or worse explanation, though.

  • 3
    Although they are the exception, some technical books published in the United States insist on using “logical quoting” throughout rather than its opposite, which is of course “illogical quoting”. The reasoning is that if you do it the other way, you’ll introduce syntactic errors in programs when describing their constructs. I happen to be an author of several such rare tomes. I don’t think this is necessarily signalling a sea change in American publishing styles; it’s only in the rarefied realm of precisionist programming primers where precisionist punctuational punctiliousness prevails.
    – tchrist
    Feb 9 '14 at 6:17
  • Here’s a sample chapter that shows an American publication using logical quoting. The kerning tables for mixing commas and quotes are such that sometimes it sometimes look as though they’re nearly superimposed, but it depends how the page-filling algorithm works just how close they get.
    – tchrist
    Feb 9 '14 at 6:24
  • "A copyrighter at work says that the practice started in the '60s as a matter of cosmetics". I hope your copywriter means the 1560s! Because that's how far back this practice goes - the beginnings of printing. Feb 9 '14 at 12:39
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    @Algernon: quotation marks weren't generally used for direct speech in English books until the 18th century. However, I assume that as soon as they started using them, printers knew from experience in other languages that periods and commas had to go inside quotation marks. Feb 9 '14 at 15:23
  • @tchrist - Just curious how hard you had to fight for that. :-)
    – Jim
    Jun 30 '18 at 17:00

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