Medicare is a U.S. federal health insurance program primarily for people aged 65 and older, as well as certain younger individuals with disabilities and those with End-Stage Renal Disease (ESRD). It consists of four parts:

• Part A (Hospital Insurance): Covers inpatient hospital stays, nursing facility care, hospice, and some home health care.
• Part B (Medical Insurance): Covers doctor visits, outpatient care, preventive services, and some home health care.
• Part C (Medicare Advantage): An alternative to Original Medicare (Parts A & B), offered by private insurance companies, often including additional benefits like vision, dental, and prescription drug coverage.
• Part D (Prescription Drug Coverage): Helps cover the cost of prescription medications.

Medicare is funded through payroll taxes, premiums, and government funding, and enrollment typically begins three months before turning 65.