The Workers' Compensation System was established by the Vermont Legislature in 1915 to compensate and protect employees who suffer personal injury by accident arising out of and in the course of employment and to protect employers by limiting their exposure from lawsuits arising out of such injuries. It is a "no-fault" insurance program that provides medical and disability benefits for work-related injuries and illnesses. It covers both traumatic injuries caused by sudden accidents and gradual onset injuries resulting from repetitive motion or stress. The system offers five basic categories of benefits: medical, temporary disability, permanency, vocational rehabilitation and death benefits. Almost all of Vermont's 350,000 workers must be covered by the system. Most employers secure coverage by purchasing workers' compensation insurance. A limited class of employers may be approved as self-insurers.