“Stupid word, that. Period. In America it means “full stop” like in punctuation. That’s stupid as well. A period isn’t a full stop. It’s a new beginning. I don’t mean all that creativity, life-giving force, earth-mother stuff, I mean it’s a new beginning to the month, relief that you’re not pregnant, when you don’t have to have a child.”
— Michelene Wandor, “Mother’s Pride,”
Guests in the Body (1986) —

PERIOD

A full pause, as is made at the end of a complete sentence. The point or character used to mark the end of a declarative sentence or to indicate an abbreviation.

Use a period...

at the end of a sentence.
I just got a new cell phone.

after a mild command (imperative sentence).
Take out the trash when you’re done with that work.

after initials.
William J. Clinton is a former United States president.

after most abbreviations.
I live on West Brook Rd., which is near the Rocky Mts.

— einfoweb.com —

Put periods within closing quotation marks, except when a parenthetical reference follows the quotation.
He said, “I may forget your name, but I never remember a face.” Smith, criticizing the apparent inaction, writes, “Donahue’s policy was to do nothing” (27).

— Owl On-Line Writing Lab —