Punctuation Help 101: Powerful Writing Help through Comma Usage (Part 1 of 2)
By Joseph Miranda

The comma (Part 1 of 2)

The most misused of all marks—the comma—will appear before you in a new way: clearly and understandably. The first step rests on mastery of its more technical uses.

In a series

When writing a series with three or more parts, use a comma to separate each part. If the series has only two parts, a comma is not necessary:

• The fish, cat, dog, bird, and ape are good friends.
• three or more items – use a comma
• The dog and cat are good friends.
• only two – don’t use a comma

Joining sentences

To join two sentences, use a comma and a coordinating conjunction—and, but, yet, etc.:

• The manager wanted Jim to finish the report, but Sally wanted Suzy to finish it.

If the two sentences are short, have the same subject, or are otherwise closely related, then you can generally omit the comma:

• Jim will start the report and Suzy will finish it.

Beware

Don’t, however, join them with only a comma. If done, you’ll have the dreaded run-on sentence:

• The supervisor yelled at his employee, the CEO stood amazed.
• Oops
• The supervisor yelled at his employee, and the CEO stood amazed.
• Fixed

So, remember to connect two sentences with a comma and a conjunction (or at least a conjunction).

Joining adjectives

When two adjectives (words that describe nouns: excited, big, interesting, etc.) individually describe the same noun, they are called coordinate adjectives. A comma should appear between any pair of coordinate adjectives. If you're not sure if the adjectives are coordinate adjectives, flip the adjectives around. If doing so doesn’t change the sentence’s meaning, use a comma; but, if doing so changes the meaning, don’t use a comma:

• The class demands that boring history book be changed.
• are boring and history coordinate adjectives?
• The class demands that history boring book be changed.
• sounds strange – no they aren’t
• The class demands that boring history book be changed.
• perfect

• Pick the juicy red tomatoes.
• are juicy and red coordinate adjectives?
• Pick the red juicy tomatoes.
• sounds fine – yes they are
• Pick the juicy, red tomatoes.
• perfect

With dates

When writing the month, day, and year, place a comma before and after the year. Do so even if the date functions as an adjective. (Some disagree with this rule, but you should be fine employing it with most audiences.) Some examples:

• On January 1, 2000, there was a massive labor strike.
• functioning as a noun
• The January 2, 2000, initiative was implemented to prevent another such strike from happening again.
• functioning as an adjective

When you use only the month and year, however, omit the commas:

• The January 2000 initiative failed miserably.

With quotations

Introduce short quotes with a comma:

• Bill said, "You get outta here right now." It was horrible.
• "My dog is sick," he observed with sadness in his eyes.

As seen in the second example, when using a comma before or after quoted material, even if the quotes show irony, place the comma inside the quotation marks:

• We should listen to the "intelligent," and you shouldn’t dismiss their opinions.

With adverb clauses

First, we should remember what clauses are: a group of words with a subject and a verb. Second, we should remember what adverbs are: words that answer one of the following questions:

• Where, why, how, when, or under what conditions a verb’s action was done.

Adverb clauses serve the same function as one-word adverbs (they answer one of above questions) and begin with one of these words:

• Where, wherever, because, since, so, as, if, after, before, etc.

When these expressions begin a sentence, we should follow them with a comma; when they end a sentence, no comma is necessary:

• Because you stayed out late yesterday, you can’t go out today.
• beginning a sentence, use a comma
• You can’t go out today because you stayed out late yesterday.
• ending a sentence, don’t use a comma
• When you leave, I’ll be here.
• beginning a sentence, use a comma
• I’ll be here when you leave.
• ending a sentence, don’t use a comma

A special note on "SO"

So begins adverb clauses. If it answers the question why, follow the same rules as mentioned above:

• So you wouldn’t get cold, I closed the window.
• so answers why I closed the window and begins the sentence
• use a comma
• I closed the window so you wouldn’t get cold.
• so answers why I closed the window and ends the sentence
• don’t use a comma

But if it tells a result, put the clause at the end of the sentence—always—and set it off with a comma:

• I worked all night, so I’m exhausted.
• so describes a result and ends the sentence (it shouldn’t ever begin it)
• use a comma

Done. A little lenthy but you've read through part 1, an in-depth discussion on comma basics. Congratulations.