Complete ACT Punctuation Rules

1. Commas

2. Semicolons

3. Colons

4. Dashes 

5. Apostrophes 

I. COMMAS

Commas should be used:

1. Before a Coordinating Conjunction to join two full sentences (Independent Clauses)

Coordinating Conjunctions, aka FANBOYS: 

For, And, Nor, But, Or, Yet, So


And and But are the two most popular conjunctions on the ACT; other coordinating conjunctions appear only rarely.

Correct: London is a very old city, but some parts of it are extremely modern.



2. Between a dependent clause and an independent clause when the dependent clause comes first.

Dependent clauses are clauses that cannot stand on their own as full sentences. They begin with Subordinating Conjunctions such as before, after, because, when, and since.

Dependent Clauses:

Because I went home

After we returned from the movie

When we visited Chicago

In the following sentence, the dependent clause is in bold and the independent clause is underlined

Correct: Because London is a very old city, it has buildings from many different eras.

When “strong” subordinating conjunctions such as (Al)though and Even Though are used to start a dependent clause, a comma should be used between the dependent clause and the independent clause, regardless of which one comes first.

Correct: London is a very old city, although some parts of it are extremely modern.



Correct: Although London is a very old city, some parts of it are extremely modern.



3. To indicate non-essential words or phrases

A non-essential clause is simply a clause that can be removed from a sentence without affecting its essential meaning. It's like a little interruption.

Non-essential clauses are always surrounded by commas.



Correct:  London, which is a very old city, has some extremely modern parts.



Incorrect:  London which is a very old city, has some extremely modern parts.



Incorrect:  London, which is a very old city has some extremely modern parts.



The same goes for single words:



Correct: London is a very old city. It does, however, have some very modern parts.



Incorrect: London is a very old city. It does however, have some very modern parts.



Incorrect: London is a very old city. It does however, have some very modern parts.



4. Around names and titles when used restrictively



Ex: John Kennedy Toole's novel, A Confederacy of Dunces, was first published more than thirty years after it was written.



The commas around the book title indicate that John Kennedy Toole only wrote one novel, and that it was called A Confederacy of Dunces.



5. After introductory words and phrases



In the beginning, there was light.


Finally, the teacher handed back the papers.



Meanwhile, Rob and I waited in the car.



6. To separate items in a list



Comma before and is optional



Correct: Hiking, skiing, and white-water rafting are my favorite things to do.



Correct: Hiking, skiing and white-water rafting are my favorite things to do.



7. To separate adjectives whose order could be reversed



Correct: The groaning, rumbling train finally pulled into the station



Correct: The rumbling, groaning train finally pulled into the station




Commas should NOT be used: 

1. Between two full sentences (Independent Clauses)

When two stand-alone sentences are joined by a comma, the result is known as a Comma Splice. Comma splices are always incorrect.

Incorrect: London is a very old city, some parts of it are extremely modern.

2. Between an independent clause and a dependent clause when the independent clause comes first.

In the following sentence, the independent clause is underlined and the dependent clause is in bold.

Incorrect: London has buildings from many different eras because it is a very old city.

3. Between two clauses with the same subject when the subject is not repeated



Repeated Subject: London is a very old city, but it has many modern buildings.



Subject Not Repeated - Correct: London is a very old city but has many modern buildings.



Subject Not Repeated - Incorrect: London is a very old city, but has many modern buildings.



4. Between Subjects and Verbs



Correct: Carlos and his sister are going to a concert tonight.


Incorrect: Carlos and his sister, are going to a concert tonight.



5. In Compound Subjects and Compound Objects



Correct: Carlos and his sister enjoy attending movies and concerts.



Incorrect Compound Subject: Carlos, and his sister enjoy attending movies and concerts.



Incorrect Compound Object: Carlos and his sister enjoy attending movies, and concerts.



6. Before or after prepositions



Correct: My birthday is my favorite day of the year.



Incorrect: My birthday is my favorite day, of the year.



Incorrect: My birthday is my favorite day of, the year.



7. Before or after the word That



Correct: I finally saw the movie that my friends had recommended.



Incorrect: I finally saw the movie, that my friends had recommended.



Incorrect: I finally saw the movie that, my friends had recommended.




AND in clauses in which that is optional and does not appear



Correct: He said (that) he would come to the movie tonight.



Incorrect: He said, he would come to the movie tonight.



8. Between two adjectives whose order cannot be reversed



Correct: I was somewhat taken aback by the sight of the big blue dog.


Incorrect: I was somewhat taken aback by the sight of the big, blue dog.



(You wouldn't say, "I was somewhat taken aback by the sight of the blue, big dog").



9. Between adjectives and nouns



Correct: The sight of the big blue dog surprised me.



Incorrect: The sight of the big blue, dog surprised me.


10. Before an open parenthesis

Correct: The Caribbean Sea contains some of the world's most stunning coral reefs (which are home to thousands of species of marine life), but many of them are in danger because of overfishing and pollution. 

Incorrect: The Caribbean Sea contains some of the world's most stunning coral reefs, (which are home to thousands of species of marine life), but many of them are in danger because of overfishing and pollution. 


II. SEMICOLONS



Semicolon = Period



Semicolons are used:


1. Between independent clauses without a conjunction



London is an old city; it has many new buildings.



2. Before However and Therefore when they are used to begin a clause



London is an old city; however, it has many new buildings.



London is an old city; therefore, it has buildings from many different eras.



III. COLONS

Colons are used:


1. Before a list



I like the following sports: hiking, swimming, and rafting.



2. Before an explanation



I talked to my teacher yesterday, and here's what she said: I should stop by tomorrow before class to discuss the test.



Colons must always follow a full sentence that can stand on its own as a
complete thought. Unlike semicolons, however, they don't have to be followed by one.



Correct: These are the kinds of fruit I like: apples, bananas and strawberries.



Incorrect: I like: apples, bananas and strawberries.


IV. DASHES

Dashes are used:



1.  To indicate non-essential statements within a sentence



Grammatically, they are identical to commas when used this way.



Correct: London - which is a very  old city - has many new buildings.



2. Before a list, an explanation, or to create a deliberate pause in a sentence



Grammatically, they are identical to colons when used this way 



Correct: I like these kinds of fruits  - apples, bananas and strawberries.


V. APOSTROPHES 




Apostrophes are used to make nouns possessive



For singular nouns, always add apostrophe + -s



The boy's ball = The ball belonging to the boy



The albatross's blanket = The blanket belonging to the albatross



For plural nouns, always add -s + apostrophe (or -es + apostrophe if the singular version ends in -s)



The boys' ball = The ball belonging to the boys



The albatrosses' blanket = The blanket belonging to the albatross



It's vs. Its



It's = It is

Its = Possessive form of it

Its' = Does not exist


Correct: It's raining outside now, but it should be sunny tomorrow.



Incorrect: Its raining outside now, but it should be sunny tomorrow.




Correct: The book is missing its cover.



Incorrect: The book is missing it's (not: it is) cover.

You're vs. Your 

You're = You are 

Your = Possessive form of you 

Correct: I'm sure whether you're (you are) coming with us tonight. 

Incorrect: I'm sure whether your coming with us tonight.

Correct: This is your jacket, right? 

Incorrect: This is you're (not: you are) jacket, right? 

They're vs. Their vs. There



They're = They are



Their = Possessive form of they



There = A Place



They're



Correct: Bob and Alice are our friends, and they're (they are) coming to dinner tonight.



Incorrect: Bob and Alice are our friends, and their/there coming to dinner tonight.



Their



Correct: The books are missing their covers.



Incorrect: The books are missing they're/there covers.



There



Correct: We went to my favorite restaurant last night, and I think I left my jacket there.



Incorrect: We went to my favorite restaurant last night, and I think I left my jacket they're/their.



Who's vs. Whose



Who's = Who is

Correct: I don't know who's (who is) at the door. 

Incorrect: I don't know whose at the door. 
Whose = Possessive  of who

Correct: I don't know whose jacket this is.

Incorrect: I don't know who's jacket this is.

That's vs. Thats

That's = That is

Thats = Does not exist 

Correct: That's (That is) my jacket lying over there. 

Incorrect: Thats my jacket lying over there. 

Hers vs. Her's 

Hers = Possessive form of her

Her's = Does not exist 

Correct: This jackets is hers.

Incorrect: This jacket is her's.