A comma (,) before the final conjunction in lists to remove ambiguity: sun, sea, sand, and semaphore.
Also called serial commas.
In a complex series, use after each element for clarity: She wore a red blouse with pearl buttons, stockings and black suede shoes, and carried a gold leather handbag.
Do not use a comma before a conjunction in a simple series unless absolutely necessary:
Part of a series on punctuation.