Despite what you may see practiced—especially in advertising, on television, and even in business letters—the fact is that the period and comma go inside the quotation marks all of the time. Confusion arises because the British system is different, and the American system may automatically look wrong to you, but it is simply one of the frequently broken rules of written English in America: The period and comma go inside the quotation marks.

Correct: The people of the pine barrens are often called “pineys.”

Incorrect: The people of the pine barrens are often called “pineys”.

However, the semicolon, colon, dash, question mark, and exclamation point fall outside of the quotation marks (unless, of course, the quoted material has internal punctuation of its own).

This measurement is commonly known as “dip angle”; dip angle is the angle formed between a normal plane and a vertical.

Built only 50 years ago, Shakhtinsk—“minetown”—is already seedy.

When she was asked the question “Are rainbows possible in winter?” she answered by examining whether raindrops freeze at temperatures below 0 °C. (Quoted material has its own punctuation.)