Final answer:
Generally, those under 65 without certain disabilities are exempt from Medicare enrollment, with the program primarily serving those 65 and older, younger individuals with disabilities on SSDI, and those with ESRD. Other specialized programs serve veterans, low-income children, and Native Americans.
Step-by-step explanation:
Medicare, established in 1965, is a United States federal health insurance program predominantly for people aged 65 or older. However, it also covers persons under 65 with certain disabilities, and individuals with End-Stage Renal Disease (ESRD). The basic eligibility criterion for the general enrollment of Medicare is to be 65 years or older.
Thus, people under the age of 65 without qualifying disabilities or conditions are typically exempt from Medicare enrollment. Exceptions include younger individuals with disabilities who receive Social Security Disability Insurance (SSDI) and those with ESRD who require dialysis or a transplant. Apart from age and disability, other publicly funded healthcare programs cater to specific groups such as military veterans (through the Veterans Health Administration), children from low-income families (through the Children's Health Insurance Program), and services focused on Native Americans (through the Indian Health Service).