Petrochemistry is the branch of the organic chemical industry that uses as raw materials natural gas, liquefied petroleum gases, refinery waste gases, naphthas, kerosene, paraffins, petroleum refining residues and some types of crude oil. The petrochemical industry is organized into first generation, second generation and third generation producers based on the transformation of various raw materials or inputs. The countries with the largest petrochemical industries are China, the United States, Japan, Germany, France and South Korea.