Serial Comma

Use a serial comma (also called an Oxford comma, Harvard comma, or series comma) between elements in a series of three or more items.

Factors of personality include extraversion, conscientiousness, openness to experience, agreeableness, and neuroticism.

If one or more items in the series already contain a comma, use semicolons between the items instead of commas.

Subjective well-being is characterized by the presence of positive affect, such as whether people feel happy and peaceful; the absence of negative affect, such as whether people feel angry or bored; and a high level of life satisfaction.

Serial commas are also used in lettered lists.