Commas
Commas are used to clarify meaning by indicating a break in a sentence. This break is smaller than the full stop indicated by a period. Commas make us pause while we’re reading, but their primary purpose is to clarify our understanding of the relationships between different parts of a sentence.
Example: Let’s eat grandma!
In this example, the speaker seems to be planning to eat their grandma—probably not the intended meaning. A comma is needed to clarify the actual meaning of the sentence.
Example: Let’s eat, grandma!
Now it’s clear that the speaker is addressing their grandma and inviting her to eat with them.
There are many rules that govern comma use, but there are four rules that you will use most often.
First, use a comma before the conjunction in compound sentences. A compound sentence is made up of two complete sentences that have been combined into one using a comma and a coordinating conjunction.
Example: Caroline had fun on her birthday, and she ate chocolate cake.
In this example, Caroline had fun on her birthday and she ate chocolate cake could both stand alone as complete sentences. To combine them into one sentence, we must use a coordinating conjunction, in this case and, and a comma that is placed before that conjunction.
The second rule also has to do with conjunctions, but this time we’ll be looking at subordinating conjunctions. When we learned how to fix run-on sentences, one solution was to use a subordinating conjunction and a comma to show the cause-and-effect relationship between the two sentences that have been combined. One part of the new sentence is called a dependent clause, because it depends on the other part of the sentence (an independent clause) to complete its thought and become a complete sentence.
The second rule is that when a dependent clause begins with a subordinating conjunction and comes before the independent clause, you must use a comma after the dependent clause.
Example: When the lecture started, Pat opened his notebook.
The dependent clause, when the lecture started, depends on the independent clause, Pat opened his notebook, to complete the thought of what happened when the lecture started. The comma is used after the dependent clause because the dependent clause comes before the independent clause.
If a dependent clause comes after the independent clause, no comma is necessary.
Example: Pat opened his notebook when the lecture started.
The third rule for comma use is to separate items in a list with commas. You may have heard of an Oxford comma; this is the name for the final comma in a list, which is placed before the coordinating conjunction (usually and or or).
Example: I had to pick up the balloons, the candles, and the cake for the party.
Finally, the fourth rule has to do with separating adjectives. When you have interchangeable adjectives describing the same noun, separate them with commas.
“Interchangeable adjectives” is what we call adjectives that are the same type. The following chart lists the different types of adjectives and some examples:
|
Opinion |
An opinion adjective explains what you think about something. Ex. difficult, funny, pretty |
|
Size |
A size adjective tells you how big or small something is. Ex. huge, wide, little |
|
Age |
An age adjective gives information about how old something is. Ex. new, ancient, young |
|
Shape |
A shape adjective describes the physical form or outline of something. Ex. round, square, flat |
|
Colour |
A colour adjective describes the colour of something Ex. red, orange, greenish |
|
Origin |
An origin adjective describes where something comes from. Ex. Cuban, eastern, lunar |
|
Material |
A material adjective describes what something is made from. Ex. wooden, stone, paper |
|
Purpose |
A purpose adjective describes what something is used for. Ex. sleeping bag (sleeping is the adjective that describes what the bag is used for) |
Adjectives that are the same type can be listed in any order. That is why they are called interchangeable adjectives.
Example: She adopted beautiful, friendly dog.
Beautiful and friendly are both opinion adjectives, describing what the subject thinks about the dog, so we include a comma to separate them.
Adjectives that are different types must be listed in a specific order. Although there are some exceptions, the general order is: opinion, size, age, shape, colour, origin, material, and finally purpose. When listing adjectives of different types, we don’t separate them with commas.
Example: She adopted a friendly brown dog.
Friendly is an opinion adjective and brown is a colour adjective. They are different types, so we don’t separate them with a comma, and we have to list them in the correct order.
These four rules will help you use commas properly in your writing. Although there are other rules for comma use, you will likely need these four the most frequently.
Practice:
Answers:
I’d like a cold, sweet ice cream cone.
If Izzy doesn’t win, I will be disappointed
He asked for turkey, cheese, and lettuce on his sandwich.
Cassidy was cold, so she put on a coat.
He went to the bright, clean building.
Tayshia took the bumpy, winding path to the park.
Improve your writing and study skills! Book an appointment with a writing advisor and/or academic coach on OSCARplus. Questions? Email skills@mcmaster.ca.