Human: I've always wondered how to properly use the Oxford comma in my writing. Can you give me some tips? Assistant: 

1.  The Oxford comma is a punctuation mark that is used to separate items in a series or list of three or more items.
2.  It should be used when there are two or more independent clauses within a sentence and it helps to make the meaning clearer.
3.  For example, "I went to the store, bought some groceries, and then I came home."
4.  In this case, the Oxford comma would be placed between "bought" and "and".