As with many English grammar rules, use of the Oxford comma (also called the serial comma) is widely debated. The Oxford comma appears before the coordinating conjunctions “and” and “or” in a list of three or more items. For example, “I enjoy coffee, tea, and hot cocoa.”
While some commonly used style guides (MLA and APA) require the use of the serial comma for clarity, other writing experts consider the serial comma unnecessary. After all, with the popularity of Tweets, emails, and texts, the more streamlined the writing, the better, right?
However, proponents of the serial comma use it to avoid ambiguous situations. For example, “At the movies, I sat next to my cousins, Sarah and Ashley.” In this example, there is confusion as to whether my cousins are Sarah and Ashley, or if I sat next to my cousins, in addition to Sarah and Ashley.
Another example is, “My favorite ice creams are vanilla, caramel and chocolate and cherry.” Here, in addition to vanilla ice cream, do I like caramel-chocolate ice cream and cherry ice cream or caramel ice cream and chocolate-cherry ice cream?
Whether you decide to include or omit the Oxford comma, be consistent throughout your writing.