OUR FRIEND, THE COMMA
Primary rule: When in doubt, leave it out.
Four Fundamentals—this will help with 90% of your comma errors
1. Items in a series: When listing three or more items, place commas
between each item and before the conjunction.
Example:
Correct: Tina, Tim, and Tom inherited Uncle Bill’s money.
Incorrect: Tina, Tim and Tom inherited Uncle Bill’s money. (Leaving the
comma out confuses the issue of inheritance.)
Incorrect: Tina, and Tim inherited Uncle Bill’s money. (Only two people are
listed—you do not need the comma).
2. Compound Sentences: When using a conjunction to link two complete
clauses (thoughts/sentences), use a comma before the conjunction (and
but, or, etc.).
Example:
Correct: My dog ran very fast, but the rabbit still escaped. (“My dog ran very
fast” is a complete sentence. “The rabbit still escaped” is a complete
sentence. “But” is a conjunction.)
Correct: My dog ran very fast and caught the rabbit. (No comma is needed.
“My dog ran very fast” is a complete sentence. “Caught the rabbit” is not).
Incorrect: My dog ran very fast, however, the rabbit got away. (“However” is
not a conjunction. The sentences need to be divided by a semi-colon or
broken into two complete sentences. “My dog ran very fast; however, the
rabbit got away” OR “My dog ran very fast. However, the rabbit got away.”
Incorrect: My dog ran very fast, the rabbit got away. (You must have a
conjunction with two complete sentences.
3. Restrictive/Non-restrictive clauses or phrases (necessary/unnecessary
words) If a phrase is essential to the meaning of the sentence, it does not
need commas. If the phrase is not essential, it should be bracketed by
commas (think of them as handles with which to lift the phrase out). This is
a broad rule—the main idea is to use two commas, not one.
Correct: Everyone who wants to go swimming should meet at the pool. (“who
wants to go swimming” is essential information).
Correct: The snowplow, which was invented in 1302, is very necessary this
winter. (The information is unnecessary, so commas go on both sides).
Incorrect: The snowplow which was invented in 1302, is very necessary this
winter. (You need a comma on both sides).
Correct: Hey, pass the salt. (Hey is an interjection. It can also be lifted out.)
4.If you begin a sentence with the following words indicating a subordinate
clause, you must always use a comma at the end of the first clause. In all
cases. No exceptions.
Since
The acronym is SWWAABIT
When
While
Although
As
Because
If
Though (and any variation-- “Even though”)
Correct: When beginning a new task, one should first read the directions.
Incorrect: If it snows tomorrow night we will not have school. (You must have a
comma after “night”—the sentence begins with “If.”)
Incorrect: We will not have school, if it snows tomorrow night. (Use a comma if
the sentence begins with a swwaabit word.)
Incorrect: Although, I am good at math I do not want to go to MIT. (The comma
goes at the end of the clause: “Although I am good at math, I do not want to
go to MIT.”)