Commas
A comma usually precedes a coordinating
conjunction (and, but, or, nor. for, so, or yet) that joins two independent
clauses in a compound sentence.
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With very short clauses, you can sometimes
omit the comma.
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Always use the comma if there is any chance
the sentence will be misread without it.
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Use a semicolon rather than a comma when the
clauses are long and complex or contain their own commas.
Use commas to set off nonrestrictive elements.
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Nonrestrictive elements are clauses, phrases,
and words that do not limit, or restrict, the meaning of the words they
modify.
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Since elements are not essential to the meaning
of a sentence they should be set off from the rest of the sentence with
commas.
Phrases
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Prepositional phrases are usually restrictive,
but sometimes they are not essential to the meaning of a sentence and are
therefore set off with commas.
Appositives
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An appositive is a noun or noun phrase that
renames a nearby noun. When an appositive is not essential to identify
what it renames, it is set off with commas.
Use commas to separate three or more items
in a series
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The next to last item in a series may often
appear without a comma. Omitting this comma may cause confusion, however,
and you will never be wrong if you include it.
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Series commas are quite often a matter of
style.
Use commas to set off parenthetical and transitional
expressions.
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Parenthetical expressions add comments or
information. They often interrupt the flow of a sentence or digress, they
are usually set off with commas.
Use commas to set off contrasting elements,
interjections, direct address, and tag questions.
Use commas to set off parts of dates, addresses,
titles, and numbers.
Dates:
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Use a comma between the day of the week and
the month...
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between the day of the month and the year...
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and between the year and the rest of the sentence,
if any.
| Example: The Gulf
War began on Thursday, January 17, 1991, with strikes
on Iraq. |
A newer style which some writers think looks
"cleaner" on the page is the exemplified below:
17 January 1991
With the day of the week it would appear
as:
Thursday, 17 January 1991.
Tip:
When there is a choice, choose a style and use it consistently. You
also might want to see if your professor, department, or your discipline
has a preferred style.
Addresses and place-names
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Use a comma after each part of an address
or place name.
Titles
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Use commas to set off professional titles
such as M.D., Ph.D., and so on, from the name preceding it
and from the rest of the sentence.
Use commas to set off most quotations.