Like chameleons, commas must match the context of a sentence.
In all of these situations: Compound sentences Introductory clauses Prepositional phrases Within lists Use one of these:
Place a comma before a coordinating conjunction.
She wanted to rescue a dog, but her husband wanted to purchase a puppy from a breeder.
The dog barked incessantly, and the neighbors complained.
Alaska was not the last state admitted into the US, nor does it have the lowest total population. (Purdue)
Other coordinating conjunctions include:
FANBOYS is a good mnemonic device.
But The Comma Splice
Examples of comma splices and corrections: incorrect: Americans speak too rapidly, this is a common complaint by foreign visitors. correct : Americans speak too rapidly; this is a common complaint by foreign visitors. correct : Foreign visitors commonly complain that Americans speak too rapidly. (Purdue)
What kinds of corrections are required? Reword the sentence to change one clause into a subordinate (or dependent) clause Add a coordinating conjunction after the comma (FANBOYS) Replace the comma with a semicolon Replace the comma with a period, question mark, or exclamation point, and capitalize the first word of the second clause comma splice
Can you find the comma splice on this bottle?
Use with words or phrases:
ending in -ing
is an infinitive (to + verb)
is an introductory word (well, yes, however, etc.)
Watching the snowfall, most students think of school closures.
To knit, you must have patience and lots of free time.
Yes, I agree that writing is sometimes painful.
Commas in Prepositional Phrases
During the Great Depression,
Although pit bulls are great dogs,
While most cars are safe,
With heightened security,
Across the street,
- While I was walking the dogs, an ambulance zipped past.
Because airfare is so expensive, we decided to drive.
After the rain stopped, I went for a run. (Purdue)
But beware…commas can be disruptive
If you don’t need a comma, don’t use a comma.
Disruptive/Incorrect comma: They bought two pizzas, but ate only one .
correct: They bought two pizzas but ate only one.
Disruptive/Incorrect comma: That man sitting in the train station, is the person I'm supposed to meet.
correct: That man sitting in the train station is the person I'm supposed to meet.