1. To separate items in a series:

2. Set off a quotation or parts of a divided quotation

3. To separate independent elements and words of direct address

4. Dates, addresses, and geographical names

5. Separating nonrestrictive phrases or clauses from the rest of the sentence.

6. After a long introductory phrase:

7. To set off parenthetical expressions

8. FANBOYS (For, And, Nor, But, Or, Yet, So): to separate independent clauses linked with a coordinating conjunction:

9. Elements of a greeting or closing: