1. Commas
When there are more than two items in a series, put a comma after each item except the last item.
Use a comma to separate certain adjectives in a series.
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Tutorial Series

2. Commas – Items, Adjectives in a Series
There are four rules for using commas in sentences:
Before a Coordinating Conjunction - FANBOYS
Items, Adjective in a Series
After Introductory Words
To Separate Out Unnecessary Words
There are also rules to separate signal tags from quotations and for standard usage such as in numbers, dates, and addresses.
However, these are special situations apart from a sentence.

3. Commas – Items, Adjectives in a Series
This tutorial covers the rule about when to use commas after introductory words.
Before Coordinating Conjunction - FANBOYS
Items, Adjectives in a Series
After Introductory Words
To Separate Out Unnecessary Words

4. Items in a Series
Using a comma when there are more than two items in a series.
I like apples and bananas.
No comma.  There are only two items.
I like apples baked with walnuts and bananas topped with chocolate and whipped cream.
No commas.  It does not make any difference if there is more than one word in the item.
When there are only two items in a series, don’t put a comma between them.

5. Items in a Series I like apples, bananas, and peaches.
There must be a comma before the word and. The standard rule is that when there are more than two items in a series, put a comma after each item except the last item.  This is true for when another word such as or is joining the last word.
Note:  Some publications and teachers do not require the use the comma before the and when there are more than two items in a series.  However, since many instructors and standardized tests do require the comma, it is safer to put a comma after each item except the last item when there are more than two items in a series.

6. Adjectives in a Series
When there is more than one adjective in a series, separate the adjective with a comma if the order can be changed and not be awkward.
Correct:
He had a long, bushy beard.
He had a bushy, long beard.
A comma is required because the adjectives can be switched around.

7. Adjectives in a Series The juggler used three yellow balls. Incorrect:
The juggler used yellow three balls.
There should not be a comma since the adjectives cannot be switched around.