The Chicago Manual of Style is the most widely used style guide in the writing industry. It is issued by the University of Chicago Press and is updated regularly. This style guide states that commas should separate items in a series. It also says if the last section consists of a pair of words joined by the word "and," a comma should still precede it. Consider this example: John cooked rice, chicken, and macaroni and cheese.
The Publication Manual of the American Psychological Association is published in Washington, D.C., and new editions are printed regularly. This grammar guide states commas should be used between items in a series of three or more. A comma should be used before the last item in a list even if the word "and" is used. Notice the following example: Jane needs apples, pears, potatoes, and bananas. A comma is used before the word "and."
The Handbook of Good English is a quick guide for authors and editors written by Edward D. Johnson. This handbook states that if the word "and" is used behind every word in a series with the exception of the last, there is no need for commas. Read this example: The car was filled with boxes and bags and books. It also states that commas should be used if the word "and" is not used. In this case, a comma should be used after every item in a series. Of course, you shouldn't end the sentence with a comma.
The Elements of Style was written by William Strunk and revised by E. B. White. This style guide states that a comma should be used after each word in a series of three or more terms except for the last word. Consider the following sentence: Mary is wearing earrings, bracelets, rings, and a necklace. In this example a comma is used before the word "and." The last comma should be omitted if the writer is referring to a group of businesses. Here's an example: Mary went to see an attorney at Johnson, Williams and Greene.