Common Punctuation Errors

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After this lesson, you will be able to avoid some of the most common mistakes in written English.

Punctuation refers to the symbols we use in writing that help make our sentences clearer. Punctuation includes the comma (,), the period (.), parentheses (), brackets [].

The Comma Splice

Whereas periods or full stops (.) indicate a long pause in speech, commas (,) indicate a slight pause. For example:

"Hi, my name is Peter." (= brief pause after 'Hi')
"Hi. My name is Peter." (= longer pause )

Native speakers often use commas in writing to indicate a brief pause:

I ordered pizza, it'll come in 30 minutes.

However, in formal writing, we are not supposed to use commas to join two complete sentences, such as "I ordered pizza" and "it'll come in five minutes." Using a comma like this is called a 'comma splice'.

To fix this, you can change the comma to a semicolon (;) or a period (.) or use a conjunction after the comma:

I ordered pizza; it'll come in five minutes.
I ordered pizza. It'll come in five minutes.
I ordered pizza, and it'll come in five minutes.

Using Commas to Separate Items

Commas are also used to separate words in a series of three or more items. You can put a comma between the last two items or leave it out. Both options are acceptable.

I like apples, bananas, and grapes.
I like apples, bananas and grapes.

Some grammarians think there should be a comma separating the last two items in a series, while others disagree. Sometimes, not using the last comma is confusing. For example:

I like my friends, Hillary Clinton and Donald Trump.

This sentence can mean both 'I like my friends, I like Hillary Clinton, and I like Donald Trump.' However, it can also mean 'I like my friends (who are) Hillary Clinton and Donald Trump.' We can clear up the sentence in the following ways:

using the final comma: I like my friends, Hillary Clinton, and Donald Trump.
rearranging the words: I like Hillary Clinton, Donald Trump and my friends.

Apostrophe for possession

When we want to indicate the plural of something, we do not use an apostrophe:

These kittens are so cute! (kittens = (plural))
These kitten’s are so cute! (incorrect: kitten's = (possessive) )

We only use apostrophes to indicate possession.

This is the kitten's ball. (= this ball belongs to the kitten)
This is the girl’s computer. (= this computer belongs to the girl)

When there is more than one owner and the word ends with an 's', we do not add an additional 's' after the apostrophe.

This is the girls’ computer. (= this computer belongs to the girls)
"This is the girls's computer" would be incorrect.

Apostrophe for contraction

We can also use apostrophes to indicate missing letters from contractions (making some words shorter).

I am → I’m
He is → He’s
It is → It’s
Can not → Can’t
We will → We’ll

Note that It's does not mean the possessive of 'it'. The possessive form of 'it' is its:

Its color is so pretty!
It's a kitten. (= It is a kitten)

Punctuation rules differ by region

In American English, the punctuation that ends a quote goes inside the quotation marks, not outside.

She said, ”This is wonderful!” (= correct in American English_)
She said, “This is wonderful”!

Exercise 1

Language Practice

Choose the correct sentence based on the rules we learned today.

Which sentence is correct?

A.
I went to a restaurant, I forgot my wallet.
B.
I went to a restaurant, but I forgot my wallet.

Which sentence is correct?

A.
This book is hers.
B.
This book is her's.

Which sentence is correct?

A.
They dont go to school today.
B.
They don't go to school today.

Which sentence is correct?

A.
She said, "I had a great time today".
B.
She said, "I had a great time today."

Which sentence is correct?

A.
It's fur was the prettiest at the pet shop.
B.
Its fur was the prettiest at the pet shop.

Which sentence is correct?

A.
Don't quit your job.
B.
Dont quit your job.

Which sentence is correct?

A.
I wanted to get some rest, I couldn't fall asleep.
B.
I wanted to get some rest, but I couldn't fall asleep.

Which sentence is correct?

A.
He warned us, "Never leave the doors unlocked."
B.
He warned us, "Never leave the doors unlocked".

Which sentence is correct?

A.
These airplanes, cars, and stuffed animals are the boys' toys.
B.
These airplanes, cars, and stuffed animals are the boys's toys.

Exercise 2

Find the Mistakes

You are an editor. Find the mistake(s) in each sentence.

Example

We went out, we went to a concert. → "We went out, and we went to a concert." / "We went out; we went to a concert." / "We went out. We went to a concert."

This is Mark's football, not your's.

Ill never know if you wont tell me!

All the boy's in the classroom have to wear blue sweaters black shoes and tie's everyday.

My house is more attractive than their's.

Cant you tell the difference between those two?

Hurry up Mark will be late!

He started crying, he felt better once again.