Medicare is a federal health insurance program in the United States that provides coverage to individuals aged 65 and older, as well as to certain younger individuals with disabilities or end-stage renal disease.

Medicare consists of four main parts: Part A, Part B, Part C (Medicare Advantage), and Part D.

- Part A covers hospital stays, skilled nursing facility care, hospice care, and some home health services.

- Part B covers doctor visits, outpatient care, medical supplies, and preventive services.

- Part C, also known as Medicare Advantage, offers an alternative to Original Medicare and includes additional benefits provided by private insurance companies.

- Part D provides prescription drug coverage.

You can typically enroll in Medicare during your Initial Enrollment Period (IEP), which starts three months before your 65th birthday month and ends three months after. There are also other enrollment periods like the General Enrollment Period and Special Enrollment Periods for certain situations.

Most people are eligible for premium-free Medicare Part A if they or their spouse have paid Medicare taxes while working. While Part A is often free, Part B usually requires a monthly premium payment. Part B covers medical services and is typically necessary to have alongside Part A.

Medicare coverage varies depending on the specific part. Part A covers inpatient hospital care, skilled nursing facility care, hospice care, and limited home health services. Part B covers doctor visits, outpatient care, medical supplies, and preventive services. Medicare Advantage plans (Part C) typically include coverage for Parts A, B, and often prescription drugs. Part D focuses solely on prescription drug coverage.

Yes, you have options for additional coverage. You can either enroll in a Medicare Advantage plan (Part C) offered by private insurance companies or purchase a Medigap (Medicare Supplement) policy to help cover costs not covered by Original Medicare.

Medicare Advantage plans are offered by private insurance companies approved by Medicare. They provide all the benefits of Original Medicare (Parts A and B) and often include additional benefits like prescription drug coverage, dental, vision, and hearing services.

The "donut hole" refers to a temporary limit on what Medicare Part D will cover for prescription drugs. Once you and your plan have spent a certain amount on medications, you enter the coverage gap. During this period, you are responsible for a higher percentage of the drug costs until you reach the out-of-pocket threshold and qualify for catastrophic coverage.

Yes, there are specific times when you can change your Medicare plan. The Annual Enrollment Period (AEP) takes place from October 15th to December 7th each year, during which you can switch between Medicare Advantage plans, switch from Original Medicare to a Medicare Advantage plan, or vice versa. There are also other enrollment periods for specific situations, such as the Medicare Advantage Open Enrollment Period.

You can use the "Physician Compare" tool on the official Medicare website to find doctors and healthcare providers who accept Medicare patients. Additionally, most doctors and hospitals in the United States accept Medicare.