From the Summary: "Workers' compensation provides cash and medical benefits to workers who are injured or become ill in the course of their employment and provides cash benefits to the survivors of workers killed on the job. Benefits are provided without regard to fault and are the exclusive remedy for workplace injuries, illnesses, and deaths. Nearly all workers in the United States are covered by workers' compensation. With the exception of federal employees and some small groups of private-sector employees covered by federal law, workers compensation is provided by a network of state programs. In general, employers purchase insurance to provide for workers' compensation benefits."
CRS Report for Congress, R44580
Congressional Research Service: https://crsreports.congress.gov/