Use a period to end a declarative sentence or sentence fragment, excluding exclamatory or imperative sentences.
The train arrived one hour early.
She left home following graduation.
Come home promptly after school.
Coming to a theater near you.
Batteries extra.
Strange. In fact, bizarre.
Use a period after an indirect question, or a suggestion or instruction that is cloaked as a question.
Tell your mother why you were late.
May we expect you to keep the noise to a minimum.
May I ask that you pay promptly.
Use only one period to end a sentence.
One of the best publishers of technical glossaries is Three Mountain Publishing, Inc.
The mayor declared emphatically that "This is the administration that our city has had in a ling time."
Use a period to punctuate abbreviations, except where otherwise specified.
(Note that there is no space following a period within an abbreviation.)
a.m.
e.g.
assn.
i.e.
Ph.D.
p.m.
Dr.
etc.
Feb.
Apr.
fig.
Use periods with a person's initials. Follow each period with a space. Omit the spaces if the initials are used in place of the name. In the latter case, the periods are optional.
R. C. KirknessR.C.K. or RCK
Use periods to differentiate integers and decimals.
16.5 gallons8.333 percent $2.75
Use periods to indicate thousands in European languages.
6.423136.417.180
Use periods after numbers and letters when the latter are used without parentheses in vertical lists.
Marketing Plan Outline:
1. Background Information
2. Problems and Opportunities
3. Marketing Objective
4. Marketing Strategy
5. Marketing Tactics
6. Marketing Budget
7. Financial Statements
Job duties:
a. Answer the telephone.
b. Open and distribute all incoming mail.
c. Record staff arrivals and departures.
d. Operate photocopy machine.
Place the period within quotation marks at the end of a sentence, even if does not punctuate the quotation.
His parting words to his assistant were "clean up that mess before I return."
Place the period inside the brackets or parentheses if the latter enclose an independent sentence.
I raised my hand to volunteer. (I had some spare time.)
Don't use a period for the enclosed sentence if the latter is a part of a larger sentence.
The meeting was held in a school (The chairman is our Superintendent of Schools) on the south side of town on a Tuesday evening in February.