Medicare is our country's health insurance program for people age 65 and older. Certain younger people can qualify, too, including those receiving disability benefits after two years, or those with permanent kidney failure or amyotrophic lateral sclerosis, Lou Gehrig's disease. The Medicare program helps with the cost of health care, but it does not cover all medical expenses or the cost of most long-term care.

If you're already receiving Social Security, you will automatically be enrolled in Medicare Parts A and B without an additional application. However, because you must pay a premium for Part B coverage, you have the option of turning it down. You will receive a red, white and blue Medicare card about two months before age 65.

Although people sign up for Medicare with the Social Security Administration, it's actually another federal agency, the Centers for Medicare and Medicaid Services, CMS, that's in charge of the Medicare program.

Medicare has four parts:
• Hospital insurance, Part A, helps pay for inpatient care in a hospital or skilled nursing facility following a hospital stay, some home health care, and hospice care.

• Medical insurance, Part B, helps pay for doctors' services and many other medical services and supplies that are not covered by hospital insurance.

• Medicare Advantage, Part C plans, are available in many areas. People with Medicare Parts A and B can choose to receive all of their health care services through one of these provider organizations under Part C.

• Prescription drug coverage, Part D, helps pay for medications doctors prescribe for treatment.

When to apply for Medicare Generally, people should apply for Medicare benefits three months before age 65.

The initial enrollment period starts three months before the month you turn 65 and extends three months past the month you turn 65. If you're not receiving Social Security benefits, you should inquire about applying for Medicare three months prior to turning age 65, so that your coverage can start the month you turn 65.

If you are 65 or older and are covered under a group health plan, either from your own or your spouse's current employment, you have a special enrollment period in which to sign up for Medicare Part B. This means that you may delay enrolling in Medicare Part B without having to wait for a general enrollment period and paying the 10 percent premium surcharge for late enrollment. It's extremely important for workers to check with their employer group health plan for specific guidance on the Medicare Part B special enrollment period.