Chapter 1: Commas

As with all punctuation, commas should help provide clarity to your writing. Whether it’s separating thoughts, phrases or lists, you’ll need a comma to keep words from running together.

In speech, commas allow a speaker the opportunity to take a breath. For readers and writers, commas provide a momentary pause before the next related thought occurs. A comma signifies the smallest break in a sentence or a slight pause to make reading easier. When in doubt, a comma should be used if a sentence could otherwise be misread.

Use Commas with Independent Clauses

As a rule of thumb, you should use a comma when preceding a conjunction, such as and, but, or, so, yet, or any other conjunction that joins two independent clauses. (An independent clause can grammatically stand alone as a sentence.)

Example:
The company wanted to make a new sofa, so they asked their customers first.

Use Commas with Introductory Dependent Clauses

When a sentence begins with a dependent clause (one that cannot stand alone as a sentence), use a comma for pause and separation. A dependent clause usually begins with if, yet, because, and, or, but, while, or when.

Example:
If our customers like the sample, we will start producing it.

However…
When a dependent clause follows an opening, main independent clause, a comma is not necessary if the dependent clause is essential to the meaning of the sentence.

Example:
We will start producing the sofa if our customers will buy it.

If the dependent clause is not essential, it should be preceded by a comma.