Berkshire Hathaway is a diversified holding company that operates a broad portfolio of subsidiaries through a decentralized management structure. The company generates revenue from insurance operations (including GEICO and various primary and reinsurance businesses), freight rail transportation through Burlington Northern Santa Fe, regulated utilities and energy infrastructure, manufacturing across industrial products and consumer goods, and services and retailing spanning private aviation, vehicle franchises, travel centers, and specialty retailers. Berkshire's business model relies on underwriting profits and investment returns from insurance operations, which generate substantial policyholder float for long-term investment, along with operational earnings from its manufacturing, transportation, utilities, and retail subsidiaries, creating a diversified revenue and earnings base.