Robert Neuwirth elaborates on the so called System D, which refers to the parallel system of informal economy throughout the world. He cross-references statistics from Nigeria and China with ponderous commercial activities, lead by informal businesses in these countries; data that was acquired during his field research. He believes informal workers are core elements who should be taken into account in all economic development strategies, as they represent entrepreneurs who identify market opportunities, exploit them and receive profits, as well, since they are part of a nation's economic growth.