Use a period to end a sentence (unless it's a question or an exclamation) or to punctuate most abbreviations.

The period offers maximum separation between ideas. (Organizations, like NCAA, MTV, and NAACP don't need a period. Neither do acronyms, like NATO or SWAT, which are abbreviations that are pronounced like words.) Sounds easy enough, right?



"A cup of hot cocoa sounds delicious. I'm so cold that I can't feel my toes."

In retrospect, wearing sandals in January was probably a bad idea. You know what's a good idea? Using a period to separate two sentences like this.

"I'll meet you in front of the movie theater at 6:30 p.m."

Did you know that p.m. stands for post meridiem, which means after midday? Look at us, dropping clock knowledge. Here's some more info: if a sentence ends with an abbreviation, like it does here, the sentence still only has one period at the end.

"Ellie wondered if dragons were real."

Even though Ellie's questioning the existence of dragons in this example, it's still correct to use a period here because the sentence is stating an indirect question.


Common mistakes

Don't do it.

No matter how a sentence ends, it never ends in two periods. Want to tell us how much you love America? "I love the U.S.A." Want to say what time you're coming over? "I'll be there at 8:00 p.m." Or maybe you were wondering when World War I started. "It started in 1939 C.E."

Two periods looks funny, anyway..


Two periods at the end of the sentence isn't the only common (mistaken) usage of double punctuation.


"He yelled, "Don't go!", and then he ran after her as fast as he could."

You've already got punctuation with the exclamation point, so you can leave the comma at home.

"I can't believe he didn't just ask, "Why can't you make it?"."

No need for that period; the question mark does the trick.


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