The Comma, Period, Semi-Colon, Colon, and Dash
The Comma
1. Separate Two Independent Clauses
What I say can make a difference, but what I write can change the world.
Canadians could ask that the CBC be abolished, or they could choose to support it.
If the two clauses are really short, fewer than about five words, the commas can be omitted.
Bakers sell bread and greengrocers sell produce.
2. Separate Items in a Series
Rowboats, canoes, kayaks, and other motorless watercraft are welcome. [Comma before 'and']
Rowboats, canoes, kayaks and other motorless watercraft are welcome. [No comma before 'and']
Dates and Addresses
He was born on May 17, 1957, in London, England, and grew up there.
When you are writing only the month and year, the comma can be omitted.
In September 2010 she moved to Nova Scotia.
Often semi-colons are used to separate complex or lengthy items in a series.
3. Separate an introductory element from rest of the sentence
This element can be a word, phrase, or subordinate clause. Learn more about subordinate clauses.
However, cookbooks predating the 19th century are scarce.
4. Around an expression
I think, however, that you are wrong.
She thought, moreover, that you would agree with her.
5. Around non-essential modifiers
John Wayne, whom I liked immensely, died in 1990.
There are also restrictive modifiers, which may look like non-restrictive modifiers but are not.
Women who chose to wear bloomers were accused of wanting to be like men.
Women were accused of wanting to be like men.
Rule 5 Summary:
Non-essential or non-restrictive modifier = set off by commas:
My sister, who likes the cold, is spending a year working up north.
Essential or restrictive modifier = no commas:
6. Before a concluding element
Use a comma, if the concluding element is considered non-essential.
7. Around the name of a person spoken to or addressed
I think, Erin, that you are absolutely right.
The Period (The Full Stop)
- End of a sentence
- Period after an abbreviation
The Semicolon
- Between two independent clauses: Use a semicolon between two independent clauses when you want to join them together and make a compound sentence. Learn more about compound sentences.
- Between Items in a Lengthy Series
The Colon
Incorrect: The paperback can be: carried easily, printed cheaply, and thrown away.
Correct: The paperback can be carried easily, printed cheaply, and thrown away.
The Dash
Use dashes sparingly in formal, academic writing. If another punctuation mark will do, use that.
- Sudden Shift in Direction: Sometimes, you may have a phrase which contradicts or negates what has gone before, and a dash is a useful way of drawing the reader's attention to that contradiction.
- Question or exclamation in the middle of a sentence