Medicare Part A is often referred to as hospital insurance. It covers inpatient hospital stays, skilled nursing facility care, hospice care, and some home health services. It is generally available to individuals who have paid Medicare taxes while working or who are eligible through their spouse's work history.

Medicare Part B is known as medical insurance. It covers doctor's visits, outpatient care, preventive services, and durable medical equipment. Part B is optional and requires a monthly premium payment. It is designed to provide essential medical services and help individuals maintain their health and well-being.

Medicare Part C, also called Medicare Advantage, offers an alternative way to receive Medicare benefits. It combines the coverage of Parts A and B with additional benefits like prescription drug coverage and sometimes dental, vision, and hearing services. Medicare Advantage plans are offered by private insurance companies approved by Medicare.

Medicare Part D is the prescription drug coverage component of Medicare. It helps individuals pay for prescription medications and is offered through private insurance companies. Part D plans have a formulary, which is a list of covered medications, and individuals pay a monthly premium along with copayments or coinsurance for their prescriptions.

Medicare Supplement, also known as Medigap, is private health insurance that helps fill the "gaps" in coverage left by Original Medicare (Parts A and B). These plans can help cover expenses such as deductibles, copayments, and coinsurance. Medigap policies are standardized and sold by private insurance companies, allowing individuals to choose the plan that best suits their needs. These plans work alongside Original Medicare and require payment of a separate monthly premium.