

The Basics
[1] To end a complete sentence
See spot run.
[2] Abbreviations
Mr., Mrs., Gov. Jenkins, Dist. Atty.
General Rule: use periods with abbreviations that appear in lower case, but don't use periods with ones that appear in upper case.
e.g. a.k.a. etc.
CEO USA NAACP
Beyond the Basics
[3] To punctuate a fragment
Sure.
The car didn't slow. It stopped. Dead.
[4] A rhetorical question
How many times do I have to tell you.
What's the point.
Style note: Depending on the feel/tone of the rhetorical question, either a period or a question mark can be appropriate.
Syntax
No space before, one space after. (I know that some people still cling to the outdated style of using two spaces after a period, but thanks to modern kerning,
this is no longer necessary.)
With quotation marks: periods go inside the closing quote. (Unless your British, then all bets are off.)
She said, "I see you."
Don't use a period directly in front of a question mark.
Usage Key
Misuse
Don't use periods to punctuate a headline or subhead
Let's Talk Style
Let's see how the pros use it
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