Comma rule in series

 In a series of three or more terms with a single conjunction, use a

Use a comma after each word except the last.

Thus write,

  red, white, and blue

  gold, silver, or copper

  He opened the letter, read it, and noted its contents.

This is also the usage of the Government Printing Office and of the

Oxford University Press.

In the names of business firms, the last comma is omitted, as,

  Brown, Shipley & Co.

  from "The Elements of Style" by William Strunk