John D. Rockefeller made his money through various business ventures including the establishment of an oil company. As a young boy, Rockefeller made money by engaging in poultry farming, selling candy and completing chores for neighbors who were willing to pay him.
Most of the success achieved by John D. Rockefeller can be attributed to his Standard Oil Company which he co-founded with his brother and four other partners. The company was founded in 1870 and grew tremendously since kerosene and gasoline had gained popularity within the United States. The company mainly grew because it bought out other refineries in the region, giving it a monopoly on the market.