The comma is a punctuation mark used to separate information within a sentence. Commas are used to separate the following:

  • Three or more items in a list
    • The recipe called for flour, eggs, and butter.
  • Complete thoughts joined by a coordinating conjunction
    • I went to the park, but John stayed home.
  • A dependent clause from an independent clause
    • Because it was raining, I decided not to go to the beach.
  • A complete thought from its introduction
    • Without proper guidance, children are likely to misbehave.
  • Non-essential information
    • The Citadel, a Halifax military landmark, has never been attacked.


A colon is a punctuation mark that is used after an independent clause to introduce information. It is most commonly used to introduce the following:

  • Lists
    • The recipe called for the following ingredients: flour, eggs, and butter.
  • Quotations
    • The academic calendar is clear on what constitutes plagiarism: “The presentation of words, ideas or techniques of another as one's own.”
  • Appositives
    • I know just how to pass this test: study hard.


A semicolon is a punctuation mark used for the following purposes (and only these purposes):

  • To emphasize the relationship between closely related independent clauses
    • Public transportation is vital to city life; many people take the bus to work or school.
  • To separate items in complex lists
    • The family business team consists of Fred Harvey, president and father; Ruth Harvey, treasurer and mother; and Jack and John Harvey, salespeople and sons.

Semicolons should not be used in the following situations:

  • To separate an independent clause from a dependent clause
  • To separate introductory information in a sentence
  • To start a list


The apostrophe is a punctuation mark used for the following purposes:

  • To show possession
    • Chocolate is Sam’s favorite ice cream flavor.
  • To indicate letters left out of contractions
    •  Sam doesn’t mind vanilla ice cream.

Single Quotation Marks

Single quotation marks are used to indicate the following:

  • Key terms or concepts
    • A ‘gerund’ is a verb ending with -ing that acts as a noun.
  • A quotation within a quotation
    • “When I asked the professor how much this assignment was worth he just said ‘Check the syllabus,’ and walked away,” Jill explained.

Double Quotation Marks:

Double quotation marks are used to indicate the following:

  • Speech or a quotation from a source
    • Einstein said "Anyone who has never made a mistake has never tried anything new."
  • As scare quotes to indicate an alternate meaning than the word would normally imply
    • Politicians say that they “care” about post-secondary student debt.
  • The title of a poem or a journal article, for example
    • “Ode on a Grecian Urn” is a poem by John Keats.
  • In academic writing to indicate information that is from another source
    • Rosemarie Morgan argues that “Hardy does appear to have had some faith in aesthetic distance” (Morgan 297).

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