Should you always use a comma before the word "or" in a series?

Answer 1

Both ways are considered correct in different circles. I work for a publishing company that follows the Chicago Manual of Style, and we always use a comma in this instance (called a serial comma or an Oxford comma). Newspapers and other folks who follow AP style don't use this comma. People in their regular lives who aren't bound by a style book tend to go back and forth. Personally, I prefer the comma for clarity's sake; I used to work for a newspaper, and I had to keep stopping myself from adding the comma at the end of a series.

Answer 2

As Stone and Bell observe, "[i]n a series of three or more members, put a comma after every member but the last" (p. 195):
"Detectives were stationed in the drawing room, on the patio and in the garden". (Stone and Bell´s example)
By analogy, the same rule applies to "or", which is also a conjunction (just like "and"):

One should try not to lose one´s temper, to insult or to contradict the boss. (mine)

Answer 3

If you are saying "I would like milk, orange juice, or coffee with breakfast." than yes. But if you are saying "I would like milk or orange juice." than no. It depends on how many items there are in the series. If there are three or more than you need to use commas after each item, but if there are two or less than commas are not needed.

Answer 4

I was always taught that you shoud in the case where you're saying, "I am going to the mall, the beach, or the movies."
BUT, I have been seeing that less and less lately and one of my professors told me it's not necessary anymore.