Serial comma

Comma before the conjunction in a list

The serial comma (also referred to as the Oxford comma or Harvard comma) is a comma placed after the penultimate term in a list (just before the conjunction) when writing out three or more terms. For example, a list of three countries might be punctuated with the serial comma as "France, Italy, and Spain" or without it as "France, Italy and Spain". The serial comma can help avoid ambiguity in some situations, but can also create it in others.

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