How to Use a Comma
We use commas often whenever we write, but few people pay attention to what this useful punctuation mark does. A comma is more than just a way to separate lists and break down long phrases into simple ones. While it may seem easy to use a comma, it’s also easy to make mistakes using it. Here are some rules you should keep in mind when using a comma:
Lists
Commas are often used to separate items together. Lists of nouns and adjectives often modify the subject, and the way you use the comma can change the meaning of the sentence. Consider the following examples:
Someone took the girls, Melissa and Kimberly, to a party.
Someone took the girls, Melissa, and Kimberly to a party.
Notice how the use of a comma can change the meaning of a sentence. The first sentence refers to two girls (Melissa and Kimberly) being taken to a party, while the second sentence refers to a group of girls, along with Melissa and Kimberly, being taken to a party.
Adjectives
Commas can also be used to separate two or more adjectives used to describe a single object or event. Consider this example:
A juicy, delicious, perfectly-cooked dish of moussaka was served as an entreé.
The adjectives “juicy,” “delicious,” and “perfectly-cooked” are coordinate adjectives, which are used in equal effect to describe the object (”dish of moussaka”). Commas are used here to prevent confusion and awkwardness when describing an object.
Dates and Places
When writing dates and the proper names of places, commas are useful to avoid confusion and to separate words. Here are some tips to bear in mind:
When writing full dates, the comma should follow the calendar date, and precede the year (example: August 24, 1992).
When writing place names, the comma should follow the primary location, and precede the bigger place where that place is located (example: Edmonton, Alberta, Canada).
Clauses
Dependent and Independent Clauses
A comma is often used to separate a dependent clause from an independent clause. Dependent clauses are phrases that cannot stand on their own as a complete sentence. Independent clauses can stand as complete sentences. A comma is used to separate a dependent and independent clause only when the dependent clause precedes the independent clause. Consider this example:
Before he picked up the string, he stopped by the harness-maker’s door to rest.
The clause “Before he picked up the string” cannot stand alone as a sentence, but the clause following it can. The comma in this sentence is used to denote a sequence of events, and to prevent the sentence from being phrased awkwardly.
Run-On Sentences and Comma Splices
The run-on sentence and the comma splice are two grammatical errors which involve the use of commas. A run-on sentence is made when two independent clauses are joined together in a compound sentence without a punctuation mark. A comma splice happens when two independent clauses are combined to form a compound sentence, but a comma is used to separate them.
Consider these examples:
Run-on sentence: Paul Bunyan was a large man he had a pet ox named Blue.
Comma splice: Paul Bunyan was a large man, he had a pet ox named Blue.
To correct these sentences, the following remedies can be applied:
Making two sentences: Paul Bunyan was a large man. He had a pet ox named Blue.
Using a semicolon: Paul Bunyan was a large man; he had a pet ox named Blue.
Commas are very useful punctuation marks when used properly. When you need to write long thoughts, list objects, or convey one or more message in a single sentence, commas can make reading and writing easier and clearer.