How did rockerfeller make his money?

John D. Rockefeller made his fortune primarily through the oil industry. He co-founded the Standard Oil Company in 1870, which dominated the oil refining sector and implemented innovative business practices, including vertical integration and aggressive pricing strategies. His company controlled a significant portion of the U.S. oil market, allowing him to amass immense wealth and become the richest man in modern history. Rockefeller's business tactics often drew criticism and led to the eventual breakup of Standard Oil in 1911 due to antitrust regulations.