Punctuations :
1. Comma
1)Commas After Introductions
Brought to you by the Purdue University Online Writing Lab
① Introductory Clauses
Introductory clauses are dependent clauses that provide background information or "set the stage" for the main part of the sentence, the independent clause. For example:
If they want to win, athletes must exercise every day. (introductory dependent clause, main clause)
Because he kept barking insistently, we threw the ball for Smokey. (introductory dependent clause, main clause)
Clue: Introductory clauses start with adverbs like after, although, as, because, before, if, since, though, until, when, etc.
② Introductory Phrases
Introductory phrases also set the stage for the main action of the sentence, but they are not complete clauses. Phrases don't have both a subject and a verb that are separate from the subject and verb in the main clause of the sentence. Common introductory phrases include prepositional phrases, appositive phrases, participial phrases, infinitive phrases, and absolute phrases.
To stay in shape for competition, athletes must exercise every day. (introductory infinitive phrase, main clause)
Barking insistently, Smokey got us to throw his ball for him. (introductory participial phrase, main clause)
A popular and well respected mayor, Bailey was the clear favorite in the campaign for governor. (introductory appositive phrase, main clause)
The wind blowing violently, the townspeople began to seek shelter. (introductory absolute phrase, main clause)
After the adjustment for inflation, real wages have decreased while corporate profits have grown. (introductory prepositional phrases, main clause)
Introductory Words
Introductory words like however, still, furthermore, and meanwhile create continuity from one sentence to the next.
The coaches reviewed the game strategy. Meanwhile, the athletes trained on the Nautilus equipment.
Most of the evidence seemed convincing. Still, the credibility of some witnesses was in question.
③ When to Use a Comma
Introductory elements often require a comma, but not always. Use a comma in the following cases:
after an introductory clause. (Does the introductory element have a subject and verb of its own?)
after a long introductory prepositional phrase or more than one introductory prepositional phrase. (Are there more than five words before the main clause?)
after introductory verbal phrases, some appositive phrases, or absolute phrases.
if there is a distinct pause. (When you read the sentence aloud, do you find your voice pausing a moment after the introductory element?)
to avoid confusion. (Might a reader have to read the sentence more than once to make sense of it?)
④ When not to Use a Comma
Some introductory elements don't require a comma, and sometimes the subject of a sentence looks like an introductory element but isn't. Do not use a comma in the following cases:
after a brief prepositional phrase. (Is it a single phrase of less than five words?)
after a restrictive (essential) appositive phrase. (See our document on appositives.)
to separate the subject from the predicate. (See below.)
Each of the following sentences may look like it requires a comma after the opening segment (marked with an x), but the opening segment is really the subject. It's sometimes easy to confuse gerund- or infinitive-phrase subjects like the following with nonessential introductory phrases, so be careful.
Preparing and submitting his report to the committee for evaluation and possible publication[x] was one of the most difficult tasks Bill had ever attempted.
To start a new business without doing market research and long-term planning in advance[x] would be foolish.
Extracting the most profit for the least expenditure on labor and materials[x] is the primary goal of a capitalist
2) Commas vs. Semicolons in Compound Sentences
A group of words containing a subject and a verb and expressing a complete thought is called a sentence or an independent clause. Sometimes, an independent clause stands alone as a sentence, and sometimes two independent clauses are linked together into what is called a compound sentence. Depending on the circumstances, one of two different punctuation marks can be used between the independent clauses in a compound sentence: a comma or a semicolon. The choice is yours.
① Comma (,)
Use a comma after the first independent clause when you link two independent clauses with one of the following coordinating conjunctions: and, but, for, or, nor, so, yet. For example:
I am going home, and I intend to stay there.
It rained heavily during the afternoon, but we managed to have our picnic anyway.
They couldn't make it to the summit and back before dark, so they decided to camp for the night.
② Semicolon (;)
Use a semicolon when you link two independent clauses with no connecting words. For example:
I am going home; I intend to stay there.
It rained heavily during the afternoon; we managed to have our picnic anyway.
They couldn't make it to the summit and back before dark; they decided to camp for the night.
You can also use a semicolon when you join two independent clauses together with one of the following conjunctive adverbs (adverbs that join independent clauses): however, moreover, therefore, consequently, otherwise, nevertheless, thus, etc. For example:
I am going home; moreover, I intend to stay there.
It rained heavily during the afternoon; however, we managed to have our picnic anyway.
They couldn't make it to the summit and back before dark; therefore, they decided to camp for the night.
3)Commas with Nonessential Elements
Some modifying elements of a sentence are essential, restricting the meaning of a modified term, while others are nonessential and don't restrict the modified term's meaning. These nonessential elements, which can be words, phrases, or clauses, are set off with commas.
Rule: Use commas before and after nonessential words, phrases, and clauses, that is, elements embedded in the sentence that interrupt it without changing the essential meaning.
Clue: If you leave out the element or put it somewhere else in the sentence, does the essential meaning of the sentence change? If so, the element is essential; if not, it is nonessential.
Nonessentialvs.EssentialThe average world temperature, however, has continued to rise significantly. (word)
Company managers, seeking higher profits, hired temporary workers to replace full-time staff. (phrase)
My uncle, who is eighty years old, walks three miles every day. (clause)The sixth-century philosopher Boethius was arrested, tortured, and bludgeoned to death. (word)
The person checking tickets at the counter asked for a form of identification. (phrase)
The woman who interviewed you is my sister. (clause)
Deciding whether an element is essential or nonessential can sometimes be tricky. For help identifying two common types of phrases that can be either essential or nonessential, see the OWL handout on verbals (handout #5) which includes information on participial phrases, as well as the handout on appositives (handout #71) which covers appositive phrases. Both of these documents address the essential/nonessential distinction for these kinds of phrases.
You can try three different interactive exercises that allow you to practice these rules, each with its own answer key.
4) Proofreading for Commas
① Compound Sentence Commas
1. Skim your paper, looking only for the seven coordinating conjunctions:
and, nor, but, so, for, or, and yet.
2. Stop at each of these words to see whether there is an independent clause (a complete sentence), on both sides of it. (For more help, see our handout on independent clauses.)
3. If so, place a comma before the coordinating conjunction. Examples:
She wanted to buy a new car, but she didn't have enough money to do so.
The wind blew fiercely, and the rain poured down.
Alaska was not the last state admitted into the US, nor does it have the lowest total population.
② Comma Splices
1. Skim your paper, stopping at every comma.
2. See whether you have an independent clause (a sentence) on both sides of the comma.
3. If so, change the sentence in one of the following ways:
reword the sentence to change one clause into a subordinate (or dependent) clause (see our handout on dependent clauses)
add a coordinating conjunction after the comma
replace the comma with a semicolon
replace the comma with a period, question mark, or exclamation point, and capitalize the first word of the second clause
comma splice: Americans speak too rapidly, this is a common complaint by foreign visitors.
correct: Americans speak too rapidly; this is a common complaint by foreign visitors.
correct: Foreign visitors commonly complain that Americans speak too rapidly.
③ Introductory Commas
Introductory commas after dependent clauses
1. Skim your paper, looking only at the first two or three words of each sentence.
2. Stop if one of these words is a dependent marker such as while, because, when, if, after, when, etc. (see our Commas After Introductions).
3. If necessary, place a comma at the end of the introductory dependent clause. Examples:
While I was writing, the phone rang.
Because the weather was bad, we decided to cancel our planned picnic.
After the last guests left the party, we had to begin cleaning the house.
④ Other introductory commas
1. Skim your paper, looking only at the first word or two of each sentence.
2. Stop if the word or phrase . . .
ends in -ing
is an infinitive (to + verb)
is an introductory word (well, yes, moreover, etc.)
3. Place a comma at the end of the introductory phrase. Examples:
To get a good grade, you must turn in all your homework problems.
Walking to work, Jim stopped for coffee at the diner.
Yes, I agree that the exam was difficult.
4. If the sentence begins with a prepositional phrase (a phrase beginning with in, at, on, between, with, etc.), place a comma after the prepositional phrase if it is longer than three words or suggests a distinct pause before the main clause. Examples:
On his way to work, Jim stopped for coffee at the diner.
In those days we wrote with a pen and paper.
Across the street from the library, an old man waited for a bus.
⑤ Disruptive Commas
General guidelines
1. Go through the paper, stopping at each comma.
2. If the comma isn't necessary for clarity or called for by a rule, get rid of it.
For disruptive commas between compound verbs or objects
1. Skim your paper, stopping only at the coordinating conjunctions: and, or, nor, but, so, for, or, and yet.
2. Check to see whether there is an independent clause (sentence) on both sides of the conjunction. If so, place a comma before the conjunction. If not, do not place a comma before the conjunction.
disruptive comma: They bought two pizzas, but ate only one.
correct: They bought two pizzas but ate only one.
For disruptive commas between subjects and verbs
1. Find the subject and verb in each of your sentences.
2. Make sure that you have not separated the subject from the verb with one comma. It's often all right to have a pair of commas between a subject and verb for nonessential clauses and phrases that might be added there, but rarely is a single comma acceptable.
disruptive comma: That man sitting in the train station, is the person I'm supposed to meet.
correct: That man sitting in the train station is the person I'm supposed to meet.
⑥ Series Commas
1. Skim your paper, stopping at the conjunctions.
2. Check to see if these conjunctions link words, phrases, or clauses written in a series.
3. If so, place commas after each word, phrase, or clause in the series (except the last one, as demonstrated in this sentence: no comma after the word clause). Examples:
People who are trying to reduce saturated fat in their diets should avoid eggs, meat, and tropical oils.
The candidate promised to lower taxes, protect the environment, reduce crime, and end unemployment.
⑦ Commas with Nonessential Elements
1. Skim your paper, looking for a phrase or clause in each sentence that explains or gives more information about a word or phrase that comes before it. (See also our handout, Commas With Nonessential Elements.)
2. If you can delete the phrase or clause and still keep the meaning, the phrase or clause is probably nonessential and needs two commas, one before and one after (unless the phrase or clause is at the end of the sentence).
3. As an alternate test for a nonessential phrase or clause, try saying "by the way" before it. If that seems appropriate to the meaning, the phrase or clause is probably nonessential. To understand the essential vs. nonessential distinction, compare the following sentences. In the first, the clause who cheat is essential; in the second, the clause who often cheats is nonessential.
Students who cheat only harm themselves.
Fred, who often cheats, is just harming himself.
5) Using Commas
The comma is a valuable, useful punctuation device because it separates the structural elements of sentences into manageable segments. The rules provided here are those found in traditional handbooks; however, in certain rhetorical contexts and for specific purposes, these rules may be broken.
1. Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.
The game was over, but the crowd refused to leave.
The student explained her question, yet the instructor still didn't seem to understand.
Yesterday was her brother's birthday, so she took him out to dinner.
2. Use commas after introductory a) clauses, b) phrases, or c) words that come before the main clause.
a. Common starter words for introductory clauses that should be followed by a comma include after, although, as, because, if, since, when, while.
While I was eating, the cat scratched at the door.
Because her alarm clock was broken, she was late for class.
If you are ill, you ought to see a doctor.
When the snow stops falling, we'll shovel the driveway.
However, don't put a comma after the main clause when a dependent (subordinate) clause follows it (except for cases of extreme contrast).
1. She was late for class, because her alarm clock was broken. (incorrect)
2. The cat scratched at the door, while I was eating. (incorrect)
3. She was still quite upset, although she had won the Oscar. (correct: extreme contrast)
b. Common introductory phrases that should be followed by a comma include participial and infinitive phrases, absolute phrases, nonessential appositive phrases, and long prepositional phrases (over four words).
Having finished the test, he left the room.
To get a seat, you'd better come early.
After the test but before lunch, I went jogging.
The sun radiating intense heat, we sought shelter in the cafe.
c. Common introductory words that should be followed by a comma include yes, however, well.
Well, perhaps he meant no harm.
Yes, the package should arrive tomorrow morning.
However, you may not be satisfied with the results.
3. Use a pair of commas in the middle of a sentence to set off clauses, phrases, and words that are not essential to the meaning of the sentence. Use one comma before to indicate the beginning of the pause and one at the end to indicate the end of the pause.
Here are some clues to help you decide whether the sentence element is essential:
If you leave out the clause, phrase, or word, does the sentence still make sense?
Does the clause, phrase, or word interrupt the flow of words in the original sentence?
If you move the element to a different position in the sentence, does the sentence still make sense?
If you answer "yes" to one or more of these questions, then the element in question is nonessential and should be set off with commas. Here are some example sentences with nonessential elements:
Clause: That Tuesday, which happens to be my birthday, is the only day when I am available to meet.
Phrase: This restaurant has an exciting atmosphere. The food, on the other hand, is rather bland.
Word: I appreciate your hard work. In this case, however, you seem to have over-exerted yourself.
4. Do not use commas to set off essential elements of the sentence, such as clauses beginning with that (relative clauses). That clauses after nouns are always essential. That clauses following a verb expressing mental action are always essential.
That clauses after nouns:
The book that I borrowed from you is excellent.
The apples that fell out of the basket are bruised.
That clauses following a verb expressing mental action:
She believes that she will be able to earn an A.
He is dreaming that he can fly.
I contend that it was wrong to mislead her.
They wished that warm weather would finally arrive.
Examples of other essential elements (no commas):
Students who cheat only harm themselves.
The baby wearing a yellow jumpsuit is my niece.
The candidate who had the least money lost the election.
Examples of nonessential elements (set off by commas):
Fred, who often cheats, is just harming himself.
My niece, wearing a yellow jumpsuit, is playing in the living room.
The Green party candidate, who had the least money, lost the election.
Apples, which are my favorite fruit, are the main ingredient in this recipe.
Professor Benson, grinning from ear to ear, announced that the exam would be tomorrow.
Tom, the captain of the team, was injured in the game.
It is up to you, Jane, to finish.
She was, however, too tired to make the trip.
Two hundred dollars, I think, is sufficient.
5. Use commas to separate three or more words, phrases, or clauses written in a series.
The Constitution establishes the legislative, executive, and judicial branches of government.
The candidate promised to lower taxes, protect the environment, reduce crime, and end unemployment.
The prosecutor argued that the defendant, who was at the scene of the crime, who had a strong revenge motive, and who had access to the murder weapon, was guilty of homicide.
6. Use commas to separate two or more coordinate adjectives that describe the same noun. Be sure never to add an extra comma between the final adjective and the noun itself or to use commas with non-coordinate adjectives.
Coordinate adjectives are adjectives with equal ("co"-ordinate) status in describing the noun; neither adjective is subordinate to the other. You can decide if two adjectives in a row are coordinate by asking the following questions:
Does the sentence make sense if the adjectives are written in reverse order?
Does the sentence make sense if the adjectives are written with and between them?
If you answer yes to these questions, then the adjectives are coordinate and should be separated by a comma. Here are some examples of coordinate and non-coordinate adjectives:
He was a difficult, stubborn child. (coordinate)
They lived in a white frame house. (non-coordinate)
She often wore a gray wool shawl. (non-coordinate)
Your cousin has an easy, happy smile. (coordinate)
The 1) relentless, 2) powerful 3) summer sun beat down on them. (1-2 are coordinate; 2-3 are non-coordinate.)
The 1) relentless, 2) powerful, 3) oppressive sun beat down on them. (Both 1-2 and 2-3 are coordinate.)
7. Use a comma near the end of a sentence to separate contrasted coordinate elements or to indicate a distinct pause or shift.
He was merely ignorant, not stupid.
The chimpanzee seemed reflective, almost human.
You're one of the senator's close friends, aren't you?
The speaker seemed innocent, even gullible.
8. Use commas to set off phrases at the end of the sentence that refer back to the beginning or middle of the sentence. Such phrases are free modifiers that can be placed anywhere in the sentence without causing confusion. (If the placement of the modifier causes confusion, then it is not "free" and must remain "bound" to the word it modifies.)
1. Nancy waved enthusiastically at the docking ship, laughing joyously. (correct)
2a. Lisa waved at Nancy, laughing joyously. (incorrect: Who is laughing, Lisa or Nancy?)
2b. Laughing joyously, Lisa waved at Nancy. (correct)
2c. Lisa waved at Nancy, who was laughing joyously. (correct)
9. 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.
Who lives at 1600 Pennsylvania Avenue, Washington, DC?
Rachel B. Lake, MD, will be the principal speaker.
(When you use just the month and the year, no comma is necessary after the month or year: "The average temperatures for July 1998 are the highest on record for that month.")
10. 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."
In 1848, Marx wrote, "Workers of the world, unite!"
11. Use commas wherever necessary to prevent possible confusion or misreading.
To George, Harrison had been a sort of idol.
Comma Abuse
Commas in the wrong places can break a sentence into illogical segments or confuse readers with unnecessary and unexpected pauses.
12. Don't use a comma to separate the subject from the verb.
An eighteen-year old in California, is now considered an adult. (incorrect)
The most important attribute of a ball player, is quick reflex actions. (incorrect)
13. Don't put a comma between the two verbs or verb phrases in a compound predicate.
We laid out our music and snacks, and began to study. (incorrect)
I turned the corner, and ran smack into a patrol car. (incorrect)
14. Don't put a comma between the two nouns, noun phrases, or noun clauses in a compound subject or compound object.
The music teacher from your high school, and the football coach from mine are married. (incorrect: compound subject)
Jeff told me that the job was still available, and that the manager wanted to interview me. (incorrect: compound object)
15. Don't put a comma after the main clause when a dependent (subordinate) clause follows it (except for cases of extreme contrast).
1. She was late for class, because her alarm clock was broken. (incorrect)
2. The cat scratched at the door, while I was eating. (incorrect)
3. She was still quite upset, although she had won the Oscar. (correct: extreme contrast)
There are five interactive exercises on using commas that you can try:
2. Hyphen
1)Using Hyphens
For information on dashes and other punctuation, see our handout Semicolons, Parentheses, Dashes, Quotation Marks, and Italics.
Two words brought together as a compound may be written separately, written as one word, or connected by hyphens. For example, three modern dictionaries all have the same listings for the following compounds:
hair stylist
hairsplitter
hair-raiser
Another modern dictionary, however, lists hairstylist, not hair stylist. Compounding is obviously in a state of flux, and authorities do not always agree in all cases, but the uses of the hyphen offered here are generally agreed upon.
1. Use a hyphen to join two or more words serving as a single adjective before a noun:
a one-way street
chocolate-covered peanuts
well-known author
However, when compound modifiers come after a noun, they are not hyphenated:
The peanuts were chocolate covered.
The author was well known.
2. Use a hyphen with compound numbers:
forty-six
sixty-three
Our much-loved teacher was sixty-three years old.
3. Use a hyphen to avoid confusion or an awkward combination of letters:
re-sign a petition (vs. resign from a job)
semi-independent (but semiconscious)
shell-like (but childlike)
4. 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
5. Use a hyphen to divide words at the end of a line if necessary, and make the break only between syllables:
pref-er-ence
sell-ing
in-di-vid-u-al-ist
For line breaks, divide already hyphenated words only at the hyphen:
mass-produced
self-conscious
For line breaks in words ending in -ing, if a single final consonant in the root word is doubled before the suffix, hyphenate between the consonants; otherwise, hyphenate at the suffix itself:
plan-ning
run-ning
driv-ing
call-ing
Never put the first or last letter of a word at the end or beginning of a line, and don't put two-letter suffixes at the beginning of a new line:
lovely (Do not separate to leave ly beginning a new line.)
eval-u-ate (Separate only on either side of the u; do not leave the initial e- at the end of a line.)
3. Brief Overview of Punctuation: Semicolon, Colon,Parenthesis, Dash, Quotation Marks, and Italics
Brought to you by the Purdue University Online Writing Lab at http://owl.english.purdue.edu
Semicolon ;
In addition to using a semicolon to join related independent clauses in compound sentences, you can use a semicolon to separate items in a series if the elements of the series already include commas. (For more help with independent clauses, look here: http://owl.english.purdue.edu/handouts/grammar/g_clause.html.)
Members of the band include Harold Rostein, clarinetist; Tony Aluppo, tuba player; and Lee Jefferson, trumpeter.
Colon :
Use a colon . . .
in the following situations:
for example:
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.
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.
in a business letter greeting.
Dear Ms. Winstead:
between the hour and minutes in time notation.
5:30 p.m.
between chapter and verse in biblical references.
Genesis 1:18
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.
Dash --
Use a dash (represented on a typewriter, a computer with no dashes in the type font, or in a handwritten document by a pair of hyphens with no spaces) . . .
in the following situations:
for example:
to emphasize a point or to set off an explanatory comment; but don't overuse dashes, or they will lose their impact.
To some of you, my proposals may seem radical--even revolutionary.
In terms of public legitimation--that is, in terms of garnering support from state legislators, parents, donors, and university administrators--English departments are primarily places where advanced literacy is taught.
for an appositive phrase that already includes commas.
The boys--Jim, John, and Jeff--left the party early.
For more help with appositives, look here: http://owl.english.purdue.edu/handouts/grammar/g_appos.html
As you can see, dashes function in some ways like parentheses (used in pairs to set off a comment within a larger sentence) and in some ways like colons (used to introduce material illustrating or emphasizing the immediately preceding statement). But comments set off with a pair of dashes appear less subordinate to the main sentence than do comments in parentheses. And material introduced after a single dash may be more emphatic and may serve a greater variety of rhetorical purposes than material introduced with a colon.
Quotation Marks " "
Use quotation marks . . .
in the following situations:
for example:
to enclose direct quotations. Note that commas and periods go inside the closing quotation mark in conventional American usage; colons and semicolons go outside; and placement of question and exclamation marks depends on the situation (see our quotation marks document).
He asked, "Will you be there?" "Yes," I answered, "I'll look for you in the foyer."
to indicate words used ironically, with reservations, or in some unusual way; but don't overuse quotation marks in this sense, or they will lose their impact.
History is stained with blood spilled in the name of "civilization."
Underlining and Italics
Underlining and italics are not really punctuation, but they are significant textual effects used conventionally in a variety of situations. Before computerized word-processing was widely available, writers would underline certain terms in handwritten or manually typed pages, and the underlining would be replaced by italics in the published version. Since word processing today allows many options for font faces and textual effects, it is generally recommended that you choose either underlining or italics and use it consistently throughout a given document as needed. Because academic papers are manuscripts and not final publications and because italics are not always easily recognized with some fonts, many instructors prefer underlining over italics for course papers. Whichever you choose, italics or underlining should be used . . .
in the following situations:
for example:
to indicate titles of complete or major works such as magazines, books, newspapers, academic journals, films, television programs, long poems, plays of three or more acts
Faulkner's last novel was The Reivers.
The Simpsons offers hilarious parodies of American culture and family life.
foreign words that are not commonly used in English
Wearing blue jeans is de rigueur for most college students.
words used as words themselves
The English word nuance comes from a Middle French word meaning "shades of color."
words or phrases that you wish to emphasize
The very founding principles of our nation are at stake!
1) to form possessives of nouns
2) to show the omission of letters
3) to indicate certain plurals of lowercase letters.
Apostrophes are NOT used for possessive pronouns or for noun plurals, including acronyms.
2)Forming possessives of nouns
To see if you need to make a possessive, turn the phrase around and make it an "of the..." phrase. For example:
the boy's hat = the hat of the boy
three days' journey = journey of three days
If the noun after "of" is a building, an object, or a piece of furniture, then no apostrophe is needed!
room of the hotel = hotel room
door of the car = car door
leg of the table = table leg
Once you've determined whether you need to make a possessive, follow these rules to create one.
• add 's to the singular form of the word (even if it ends in -s):
the owner's car
James's hat
• add 's to the plural forms that do not end in -s:
the children's game
the geese's honking
• add ' to the end of plural nouns that end in -s:
houses' roofs
three friends' letters
• add 's to the end of compound words:
my brother-in-law's money
• add 's to the last noun to show joint possession of an object:
Todd and Anne's apartment
3) Showing omission of letters
Apostrophes are used in contractions. A contraction is a word (or set of numbers) in which one or more letters (or numbers) have been omitted. The apostrophe shows this omission. Contractions are common in speaking and in informal writing. To use an apostrophe to create a contraction, place an apostrophe where the omitted letter(s) would go. Here are some examples:
don't = do not
I'm = I am
he'll = he will
who's = who is
shouldn't = should not
didn't = did not
could've= could have (NOT "could of"!)
'60 = 1960
4) Forming plurals of lowercase letters
Apostrophes are used to form plurals of letters that appear in lowercase; here the rule appears to be more typographical than grammatical, e.g. "three ps" versus "three p's." To form the plural of a lowercase letter, place 's after the letter. There is no need for apostrophes indicating a plural on capitalized letters, numbers, and symbols (though keep in mind that some editors, teachers, and professors still prefer them). Here are some examples:
p's and q's = a phrase indicating politeness, possibly from "mind your pleases and thankyous"?
Nita's mother constantly stressed minding one's p's and q's.
three Macintosh G4s = three of the Macintosh model G4
There are two G4s currently used in the writing classrom.
many &s = many ampersands
That printed page has too many &s on it.
the 1960s = the years in decade from 1960 to 1969
The 1960s were a time of great social unrest.
Don't use apostrophes for possessive pronouns or for noun plurals.
Apostrophes should not be used with possessive pronouns because possessive pronouns already show possession -- they don't need an apostrophe. His, her, its, my, yours, ours are all possessive pronouns. Here are some examples:
wrong: his' book
correct: his book
wrong: The group made it's decision.
correct: The group made its decision.
(Note: Its and it's are not the same thing. It's is a contraction for "it is" and its is a possesive pronoun meaning "belonging to it." It's raining out= it is raining out. A simple way to remember this rule is the fact that you don't use an apostrophe for the possesives his or hers, so don't do it with its!)
wrong: a friend of yours'
correct: a friend of yours
wrong: She waited for three hours' to get her ticket.
correct: She waited for three hours to get her ticket.
5) Proofreading for apostrophes
A good time to proofread is when you have finished writing the paper. Try the following strategies to proofread for apostrophes:
• If you tend to leave out apostrophes, check every word that ends in -s or -es to see if it needs an apostrophe.
• If you put in too many apostrophes, check every apostrophe to see if you can justify it with a rule for using apostrophes.
We have interactive exercises on using apostrophes: you can try apostrophe exercise one or apostrophe exercise two.