Top 10 Rules of Punctuation

While there are no hard and fast rules about punctuation, there are good style guidelines. This is a list of our ten most commonly used punctuation marks and a guide to their use.

10. Comma

Use commas to separate independent clauses in a sentence, for example:

The game was over, but the crowd refused to leave.

Yesterday was her brother’s birthday, so she took him out to dinner.

Use commas after introductory words, phrases, or clauses that come before the main clause:

While I was eating, the cat scratched at the door.

If you are ill, you ought to see a doctor.

NOTE: You should not do the reverse of this. For example, the following two cases are wrong:

The cat scratched at the door, while I was eating.

You ought to see a doctor, if you are ill.

Introductory words that should be followed by a comma are: yes, however, and well. For example: Yes, you can come to the party

Use a pair of commas to separate an aside from the main body of the sentence. For example:

John and Inga, the couple from next door, are coming for dinner tonight.

You can test this by removing the aside from the sentence. If the sentence still reads correctly, you have probably used the commas as you should. In the case above, this would render: John and Inga are coming for dinner tonight.

Do not use commas to separate essential elements of the sentence. For example:

Students who cheat only harm themselves.

The baby wearing a yellow jumpsuit is my niece.

The Oxford Comma

I prefer the Oxford comma when dealing with lists. It is also known as the Serial Comma or the Harvard Comma. The Oxford comma is much more widespread in American English than British English. When using the Oxford comma, all items in a list of three or more items are separated. For example:

I love apples, pears, and oranges.

Note the comma after “pears”. Many people prefer not to use this style and will omit the final comma. We call this the Oxford comma because it is the standard method taught at Oxford University.

Use commas to set off all geographical names, items in dates (except the month and day), addresses (except the street number and name), and titles in names.

Birmingham, Alabama, gets its name from Birmingham, England.

July 22, 1959, was a momentous day in his life.

Occasionally, you will see a comma between a house number and street. This is not wrong, it is just old fashioned. It is not done in modern times, however.

Use a comma to shift between the main discourse and a quotation.

John said without emotion, “I’ll see you tomorrow.”

“I was able,” she answered, “to complete the assignment.”

Use commas if they prevent confusion:

To George, Harrison had been a sort of idol.

9. Period or Full Stop

The primary use of a period is to end a sentence. Its second important use is for abbreviations. There are stylistic differences here. I will discuss both.

Fowler

Martin Fowler, author of Modern English Usage, says that we should place a period at the end of an abbreviation only when the final letter of the abbreviation is not the final letter of the expanded word. For example:

Jesus Christ was born c. 4-6AD

The abbreviation is for the word “circa” – as it ends in an ‘a’ and the abbreviation is normally ‘c’ – we include the period.

Mr Jones was happy to see his wife

St Patrick lived in Ireland

In the first case above, “Mr” is an abbreviation for mister. Because mister ends in an ‘r’ and the abbreviation includes that ‘r’, we omit the period.

Other

The other use of the period for abbreviations is to always include the period, regardless of whether the final letter is included.

Mr. Jones was happy to see his wife

If an abbreviated phrase is pronounced, we do not include periods. For example: NASA is correct, N.A.S.A is incorrect. In some cases the periods are omitted even when the word is not pronounced, usually because it is a very commonly known term. For example: UCLA (University of California, Los Angeles).

In the case of a word like et cetera (etc.,) we always include the period.

8. Question Mark

The question mark is a fairly easy punctuation mark to use. It has one use, and one use alone. It goes at the end of a sentence which is a question. For example:

How many will be at the party?

you do not include a period when using a question mark. You also do not use a combination of question marks and exclamation marks in formal writing, though this is gaining acceptance in informal writing – particularly on the internet.

One thing to be careful of is to not include a question mark when it is not needed:

WRONG: I wonder how many people will come to the party?

While you are expressing a thought that seems to require an answer, you are doing so with a statement. This is the most common mistake made when using a question mark.

7. Exclamation Mark

Only use this when issuing a command or speaking forcefully! As in the case of the question mark, do not follow this with a period and do not combine it with other punctuation marks. Oh, and only one is needed. Two or three exclamation marks in a row is completely unnecessary.

6. Quote Marks

Quotation marks are used to quote another person’s words exactly, whether they be spoken, or written. For example:

John said, “We are going shopping.” – note the capitalization of “We”. You should do this unless you are quoting in a run-on sentence:

John said “we are going shopping” because they had no milk. Note the omission of the comma in this case also.

If you are quoting a person who is quoting another person, use a single quotation mark like this:

John said, “My neighbor yelled at me today! He said ‘get off my lawn!’”

When introducing a quotation after an independent clause, use a colon and not a comma to begin:

As D. H. Nachas explains, “The gestures used for greeting others differ greatly from one culture to another.” (not an independent clause)

D. H. Nachas explains cultural differences in greeting customs: “Touching is not a universal sign of greeting. (this is an independent clause)

Quotation marks can also be used to denote irony or sarcasm, or to note something unusual about it:

The great march of “progress” has left millions impoverished and hungry.

Punctuation with quotations

Punctuation that belongs to the original quote should be inside the quote marks. Punctuation relating to the entire sentence should be outside.

Philip asked, “Do you need this book?”

Does Dr. Lim always say to her students, “You must work harder”?

Always put colons and semicolons outside quotes. Put commas and periods inside quotations unless followed by parenthesis:

He said, “I may forget your name, but I never remember a face.”

Mullen, criticizing the apparent inaction, writes, “Donahue’s policy was to do nothing” (27).

5. Colon

A colon should be used after a complete statement in order to introduce one or more directly related ideas, such as a series of directions, a list, or a quotation or other comment illustrating or explaining the statement. For example:

The daily newspaper contains four sections: news, sports, entertainment, and classified ads.

The strategies of corporatist industrial unionism have proven ineffective: compromises and concessions have left labor in a weakened position in the new “flexible” economy.

The colon is also used to separate chapter and verse from the bible (I Parlipomenon 12:30), to separate hours, minutes, and seconds: 13:49:08, and as eyeballs in smiley faces.

4. Semicolon

Use a semicolon to join related independent clauses in compound sentences. For example:

Jim worked hard to earn his degree; consequently, he was certain to achieve a distinction.

Jane overslept by three hours; she was going to be late for work again.

The semicolon is also used to separate items in a series if the elements of the series already include commas. For example:

Members of the band include Harold Rostein, clarinetist; Tony Aluppo, tuba player; and Lee Jefferson, trumpeter.

3. Apostrophe

The apostrophe has three uses:

1) to form possessives of nouns
2) to show the omission of letters
3) to indicate certain plurals of lowercase letters.

Forming possessives

the boy’s hat

three day’s journey

If the noun after “of” is a building, an object, or a piece of furniture, then no apostrophe is needed. For example: The car door.

Showing omission

He’ll go = He will go

could’ve = could have (Not “could of”!)

Forming plurals

Apostrophes are used to form plurals of letters that appear in lowercase. For example:

Mind your p’s and q’s

2. Parentheses

Parentheses are occasionally and sparingly used for extra, nonessential material included in a sentence. For example, dates, sources, or ideas that are subordinate or tangential to the rest of the sentence are set apart in parentheses. Parentheses always appear in pairs.

Before arriving at the station, the old train (someone said it was a relic of frontier days) caught fire.

1. Dash or Hyphen

Dash

Use the dash to emphasize a point or to set off an explanatory comment; but don’t overuse dashes, or they will lose their impact. A dash is typically represented on a computer by two hyphens with no spaces before, after, or between the hyphens.

To some of you, my proposals may seem radical–even revolutionary.

It is also used for an appositive phrase that already includes commas.

The boys–Jim, John, and Jeff–left the party early.

As you can see, the dash can be used in the same way as parentheses.

Hyphen

Use a hyphen to join two or more words serving as a single adjective before a noun:

chocolate-covered peanuts

Don’t use the hyphen when the noun comes first:

The peanuts are chocolate covered

Use a hyphen with compound numbers: Forty-five

You should also use a hyphen to avoid confusion in a sentence:

He had to re-sign the contract
He had to resign his job

Use a hyphen with the prefixes ex- (meaning former), self-, all-; with the suffix -elect; between a prefix and a capitalized word; and with figures or letters:

ex-husband
self-assured
mid-September
all-inclusive
mayor-elect
anti-American
T-shirt
pre-Civil War
mid-1980s

Sourced under fair use from the Purdue University Online Writing Lab