Aon is a global professional services firm providing insurance brokerage, reinsurance brokerage, human capital consulting and risk management advisory services to businesses navigating complex insurance and workforce decisions. As an insurance broker, Aon helps companies design and place commercial insurance coverage with insurers, earning commissions and fees for that advisory and placement work rather than carrying underwriting risk itself. The firm's human capital practice advises on employee benefits, retirement plans and compensation strategy, giving it a second major business line beyond core insurance brokerage. Aon has grown substantially through acquisitions over the decades, consolidating smaller brokerages and consulting practices, and competes most directly with Marsh McLennan and Willis Towers Watson in a global insurance brokerage market with only a small number of truly global-scale competitors.