Punctuation is an essential element of good writing because it makes the author’s meaning clear to the reader. Although precise
punctuation styles may vary somewhat among published sources, there are a number of fundamental principles worthy of consideration.
Discussed below are the punctuation marks used in English:
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comma
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apostrophe
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semicolon
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quotation marks
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colon
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parentheses
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period
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dash
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question mark
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hyphen
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exclamation point
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CommaThe comma is the most frequently used mark of punctuation in the English language. It signals to the reader a pause, which
generally clarifies the author’s meaning, and establishes a sensible order to the elements of written language. Among the
most typical functions of the comma are the following:
1. It can separate the clauses of a compound sentence when there are two independent clauses joined by a conjunction, especially
when the clauses are not very short:
2. It can separate the clauses of a compound sentence when there is a series of independent clauses, the last two of which
are joined by a conjunction:
3. It is used to precede or set off, and therefore indicate, a nonrestrictive dependent clause (a clause that could be omitted
without changing the meaning of the main clause):
4. It can follow an introductory phrase:
5. It can set off words used in direct address:
6. The comma can separate two or more coordinate adjectives (adjectives that could otherwise be joined with and) that modify one noun:
Note that cumulative adjectives (those not able to be joined with and) are not separated by a comma:
7. Use a comma to separate three or more items in a series or list:
Note that the comma between the last two items in a series is sometimes omitted in less precise style:
8. Use a comma to separate and set off the elements in an address or other geographical designation:
9. Use a comma to set off direct quotations (note the placement or absence of commas with other punctuation):
10. A comma is used to set off titles after a person’s name:
SemicolonThe semicolon has two basic functions:
1. It can separate two main clauses, particularly when these clauses are of equal importance:
2. It can be used as a comma is used to separate such elements as clauses or items in a series or list, particularly when
one or more of the elements already includes a comma:
ColonThe colon has five basic functions:
1. It can introduce something, especially a list of items:
2. It can separate two clauses in a sentence when the second clause is being used to explain or illustrate the first clause:
3. It can introduce a statement or a quotation:
4. It can be used to follow the greeting in a formal or business letter:
5. In the U.S., the colon separates minutes from hours, and seconds from minutes, in showing time of day and measured lengths
of time:
PeriodThe period has two basic functions:
1. It is used to mark the end of a sentence:
2. It is often used at the end of an abbreviation:
(Note that another period is not added to the end of the sentence when the last word is an abbreviation.)
Question Mark and Exclamation PointThe only sentences that do not end in a period are those that end in either a question mark or an exclamation point.
Question marks are used to mark the end of a sentence that asks a direct question (generally, a question that expects an answer):
Exclamation points are used to mark the end of a sentence that expresses a strong feeling, typically surprise, joy, or anger:
ApostropheThe apostrophe has two basic functions:
1. It is used to show where a letter or letters are missing in a contraction:
2. It can be used to show possession:
a. The possessive of a singular noun or an irregular plural noun is created by adding an apostrophe and an s:
b. The possessive of a regular plural noun is created by adding just an apostrophe:
Quotation MarksQuotation marks have two basic functions:
1. They are used to set off direct quotations (an exact rendering of someone’s spoken or written words):
Note that indirect quotes (which often are preceded by that, if, or whether) are not set off by quotation marks:
2. They can be used to set off words or phrases that have specific technical usage, or to set off meanings of words, or to
indicate words that are being used in a special way in a sentence:
Note that sometimes single quotation marks (the ’stamen.’), rather than double quotation marks as above (the “stamen.”), may
be used to set off words or phrases. What is most important is to be consistent in such usage.
ParenthesesParentheses are used, in pairs, to enclose information that gives extra detail or explanation to the regular text. Parentheses
are used in two basic ways:
1. They can separate a word or words in a sentence from the rest of the sentence:
(Note that the period goes outside the parentheses, because the words in the parentheses are only part of the sentence.)
2. They can form a separate complete sentence:
(Note that the period goes inside the parentheses, because the words in the parentheses are a complete and independent sentence.)
DashA dash is used most commonly to replace the usage of parentheses within sentences. If the information being set off is in
the middle of the sentence, a pair of dashes is used; if it is at the end of the sentence, just one dash is used:
HyphenA hyphen has three basic functions:
1. It can join two or more words to make a compound, especially when so doing makes the meaning more clear to the reader:
2. It can replace the word “to” when a span or range of data is given:
3. It can indicate a word break at the end of a line. The break must always be between syllables:
Garner, Bryan A. A Dictionary of Modern American Usage. New York: Oxford University Press, 1998.