The shell sort is a "diminishing increment sort", better known as a "comb sort" to the unwashed programming masses. The algorithm makes multiple passes through the list, and each time sorts a number of equally sized sets using the Insertion Sort. The size of the set to be sorted gets larger with each pass through the list, until the set consists of the entire list. (Note that as the size of the set increases, the number of sets to be sorted decreases.)