Oxford Comma

A comma is required for clarity after the penultimate (second-last) item in the list: “In the garden shed you will find a lawnmower, hedge shears, several pairs of gloves, and boots.”

The boldfaced comma is required for clarity, to indicate that the last item in the list is not part of the preceding item. If there were no comma before “boots,” the reader might think that “several pairs” refers to “boots” as well as “gloves.”