In a Series

Use a comma to separate items in a series (three or more things).You should even place a comma between the last two, although some writing style guidelines now omit this comma. In academic culture, we still use the serial or “Oxford” comma, so even punctuation rules have a rhetorical context. In some situations, you may not use the serial comma, but in academic writing you should, as illustrated in these examples: She stayed up all night watching scary movies and ate popcorn, peanuts, and chocolate.She ran into the house, shut the door, and locked all of the locks because she thought a werewolf was behind her.