It's more common for the British to put them outside and it's more common for U.S. writers to put them inside. But it's not simple or universal. If you're serious about it, you need to obtain a "style guide," "style manual," or "style sheet" for the publication you are writing for and follow whatever it says. Here's a blog entry that discusses it from the point of view of the U.S. APA style guide: http://blog.apastyle.org/apastyle/2011/08/punctuating-around-quotation-marks.html The "quick chart" at the top is your quick answer. But the most important sentence, in my opinion, is this one: "As a final note, we’d like to say... that not all fields or publishers in the United States and Canada use American style punctuation."

Unless you're applying for a job as an editor in publishing, it really doesn't matter too much. Yes, we can put the full stop before the quotation marks, but we can also put them inside the quotation marks as most Americans do. I wouldn't worry about it, if I were you.

In general, I don't think anyone would mind, unless there is a style guide you have to follow. I notice that I do both but you should really be consistent. Here is one UK English style guide: https://www.theguardian.com/guardian-observer-style-guide-a

That I didn't know about. Thanks for clarifying!

Yes, don't talk about 'periods' to British people. For us it means, well, you know....