John D. Rockefeller was born in 1839 in New York and studied business in Cleveland. He worked as a bookkeeper and started a grocery business with a partner. Rockefeller saw potential in the oil industry and built his own refinery, pursuing efficiency. He partnered with Henry Flagler, integrating operations vertically. Together they formed Standard Oil, gaining control of 90% of the oil industry by aggressive expansion. Rockefeller retired in his late 50s and donated much of his fortune to universities, medical research, and other charities. He revolutionized business with vertical integration and set a model for philanthropy.