I am confused as to when commas are supposed to be used before the conjunction and.

This question answers it but I am still a bit confused.

For instance the following two sentences:

  • I am going to buy apples, oranges, and bananas at the store.
  • I am going to buy apples, oranges and bananas at the store.

Which of the above sentences is the correct usage of a comma?


1 Answer 1


Such use of a comma is often called a "serial comma" or an "Oxford comma".

It is typically a matter of style, at least where there is no ambiguity. For example, with or without the comma, your example statement

I am going to buy apples, oranges[,] and bananas at the store.

is not ambiguous. Omission/inclusion of the comma is optional. (According to Wikipedia, use of the Oxford comma is more popular in American English than British English.)

In certain situations the serial comma can resolve some ambiguity. In these cases it should be used:

I am going to buy soup, broccoli[,] and asparagus.

  • In nearly all cases where the sentence is ambiguous without an Oxford comma, however, it is also ambiguous (though in different ways) with an Oxford comma. Your example here is ambiguous both with and without: “I am going to buy soup: broccoli and asparagus (soup)” without, and “I am going to buy soup (broccoli soup) and asparagus” with. Sep 13, 2013 at 18:55
  • That's a fair point, but in a practical sense, the ambiguity is significantly reduced with the Oxford comma. (At the very least we know that asparagus will be bought.)
    – badroit
    Sep 13, 2013 at 23:51

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