What function does a separator comma serve?

The function of a separator comma is to separate three or more elements in a series, which helps clarify the items listed and enhances readability. For instance, when writing a sentence such as "I bought apples, oranges, and bananas," the comma before "and" (known as the Oxford comma, though sometimes optional) separates the individual items in the series. This use prevents confusion and ensures that each element is recognized as distinct.

In contrast, while commas do have roles in other contexts—such as indicating direct address, introducing a list, or separating independent clauses—the primary function being highlighted in this case is specifically about separating multiple items within a single list or series. This clear delineation of items helps readers to better understand the sentence structure and the relationships between the items being presented.