Punctuation of sentence
The comma is the most often used mark of punctuation within a sentence. In general, commas separate parts of a sentence. Adding unnecessary commas or omitting necessary ones can confuse a reader and obscure the meaning of a sentence.
Use a Comma
To Separate Independent Clauses of a Compound Sentence Linked by a Coordinating Conjunction—Such as and, but, yet, for, or, or nor—unless the Compound Sentence is very brief
Almost every person knows how to earn money, yet not one in a million knows how to spend it.
Bill is not in the office today, but he will be here tomorrow.
To Set Off Most Introductory Elements:
An introductory element modifies (describes) a word or words in an independent clause that follows.
Having rid themselves of their former rulers, the people now disagreed on the new leadership.
Although the details have not been fully developed, scientists are confident that people will reach the stars.
Politically, our candidate has proved to be inept.
Hurt, she left the room quickly.
Pleased with the result, he appraised his work.
In 1988, 300 people won in the lottery.
To Set Off Nonrestrictive Elements:
Since it restricts or limits the meaning of the word or words it applies to, a restrictive element is essential to the meaning of the sentence and thus cannot be omitted.
The novel that she wrote in 1989, won a literary award.
Employees who started before November 1, will be entitled to two more vacation days per year.
To Set Off Interrupting Words or Phrases:
There are several different kinds of interrupters. These include words of direct address, appositives, contrasting expressions, interjections, parenthetical expressions, and transitional words.
Words of direct address: These are words that tell to whom a comment is addressed.
You realize, Mary, that we may never return to Paris.
Jim, where have you been?
Interjections: Use a comma to set off any interjection. Examples of interjections include well, my, oh, yes, and no.
Oh, here's our new neighbour
Why, you can't mean that!
Well, can you imagine that!
Parenthetical expressions:Use commas to set off expressions that explain by providing additional information.
You may, if you insist, demand a retraction.
If you wouldn't mind, please leave your raincoat and umbrella on the porch.
Transitional words:: Transitional expressions include however, indeed, consequently, as a result, of course, for example, in fact, and so forth. Use a comma to distinguish these expressions from the rest of the sentence.
Still, you must agree that he knows his business.
The use of pesticides, however, has its disadvantages.
He knew, nevertheless, that all was lost.
To Separate Items in a Series :
Use a comma to separate words, phrases, and clauses that are part of a series of three or more items.
The Danes are an industrious, friendly, generous, and hospitable people.
The chief agricultural products of Denmark are butter, eggs, potatoes, beets,
wheat, barley, and oats.
Use a Semicolon To
In general, a semicolon is used to separate parts of a sentence—such as independent clauses, items in a series, and explanations or summaries—from the main clause.
To Separate Independent Clauses Not Joined by a Simple Conjunction
The house burned down; it was the last shattering blow.
The war must continue; we will be satisfied only with victory.
We have made several attempts to reach you by telephone; not a single call has been returned.
To Separate Independent Clauses Joined by a Conjunctive Adverb, Such as however, nevertheless, otherwise, therefore, besides, hence, indeed, instead, nonetheless, still, then
The funds are inadequate; therefore, the project will close down.
Enrolments exceed all expectations; however, there is a teacher shortage.
He knew the tickets for the performance would be scarce; therefore, he arrived at the concert hall two hours early.
A comma is generally used after a conjunctive adverb.Commas are optional, however, with such one-syllable conjunctive adverbs as thus and hence; they are frequently omitted as well when therefore, instead, or any of several other conjunctive adverbs are placed at the end of clauses.
She skipped her lunch; thus she was ravenously hungry by 4:00.
He did not take notes; he borrowed hers instead.
To Separate Long or Possibly Ambiguous Items in a Series,Especially When Those Items Already Include Commas
The elected officers are Robert Harris, President; Charles Lawrence, Vice President; Samantha Jill, Treasurer; and Elisabeth Fink, Secretary.
During the parade, the marchers wore red, green, and blue uniforms; carried silver banners; and sang songs.
Use a Colon
As a mark of introduction, the colon tells the reader that the first statement is going to be explained by the second or signals that a quotation or series will follow. In effect, the colon is a substitute for such phrases as for example and namely. A colon can often be interchanged with a dash, although a dash indicates a less formal and more abrupt shift.
To Introduce a Long Formal Statement, Summary, Explanation, Quotation, or Question
This I believe: All men are created equal and must enjoy equally the rights that are inalienably theirs.
They cannot pay their monthly bills because their money is tied up in their stocks and bonds: they are paper-rich and cash-poor.
'It is a good thing to be old early: to have the fragility and sensitivity of the old, and a bit of wisdom, before the years of planning and building have run out'.—Martin Gumbert
Richards replied: "You are right. There can be no unilateral peace just as there can be no unilateral war. No one contests that view." (Note: Use a comma, not a colon, if the quotation is a single sentence.)
This is the issue: Can an employer dismiss an employee simply because the employee laughs loudly? (Note that the first word of the sentence following the colon is capitalized. This applies to formal statements as well as to questions.)
To Introduce a Series or List of Items,Examples, or the Like
The three committees are as follows: membership, finance, and nominations.
He named his five favorite poets: Byron, Keats, Tennyson, Hardy, and Dickinson.
The colon should not be used after of or after a verb.
The committee consisted of nine teachers, twelve parents, and six business leaders.
Possible choices include games, tapes, books, and puzzles.
To Follow the Salutation of a Formal Letter or Speech
Dear Mr. Brodwin:
My fellow Americans:
To Whom It May Concern:
To Follow the Name of the Speaker in a Play
Ghost: Revenge his foul and most unnatural murder.
To Separate Parts of a Citation
Journal of Transcendentalism 15:251–255
To Separate Hours from Minutes in Indicating Time
A dash is used to show sudden changes in thought or to set off certain sentence elements. Like the exclamation point, dashes are dramatic and thus should be used sparingly in formal writing. Do not confuse the dash with the hyphen.
Use a Dash To
Mark an Abrupt Change in Thought, Shift in Tone, or Grammatical Construction in the Middle of a Sentence
He won the game—but I'm getting ahead of the story.
She told me—did she really mean it?—that she will inform us of any changes ahead of time from now on.
Suggest Halting or Hesitant Speech
"Well—er—it's hard to explain," he faltered.
Madame de Vionnett instantly rallied.
"And you know—though it might occur to one—it isn't in the least that he's ashamed of her. She's really—in a way—extremely good looking."—Henry James
Indicate a Sudden Break or Interruption before a Sentence Is Completed
"Harvey, don't climb up that—." It was too late.
If they discovered the truth—he did not want to think of the consequences.
Add Emphasis to Parenthetical Material or Mark an Emphatic Separation between Parenthetical Material and the Rest of the Sentence
His influence—he was a powerful figure in the community—was a deterrent to effective opposition.
The car he was driving—a gleaming red convertible—was the most impressive thing about him.
Replace an Offensive Word or Part of One
Where the h— is he?
Where's that son of a —?
The Declaration of Independence was signed on July 4, 1776.
Pearl Harbor was bombed on Sunday, December 7, 1941.
Her friend lives at 35 Fifth Avenue, New York, N.Y.
She moved from 1515 Halsted Street, Chicago, Illinois.