All Medicare is divided into four Parts A, B, C and D.

Part A is insurance covering hospital care, nursing and home health care and hospice care for the terminally ill. The insurance generally covers 80 percent of costs. Most people are automatically enrolled in Part A when they turn 65 and pay no premium since this original part of Medicare is funded by payroll deductions.

Part B is outpatient medical insurance, covering doctor visits, lab tests, and medical supplies and services prescribed by doctors.

Many people not yet near retirement think this, too, is free. It is not.

Marion Ingram, of Strathmere, said she thinks the general public does not understand that she and her fellow retirees pay through Social Security deductions for Part B outpatient coverage and for prescription coverage - and buy supplemental coverage for what Medicare does not cover.

"It's amazing. Even our own children, you'd think they'd understand, but it's a whole different world to them," Ingram said. "I know a lot of them seem to think us old people are getting all of this stuff for nothing."

Part C, also know as Medicare Advantage, offers managed care plans from private insurers as an alternative to Part B coverage.

Medicare Advantage plans often include additional benefits, such as hearing aids, dental services and eyeglasses, Medicare spokesman Jeffrey Hall said. Some include prescription drugs, which most get under the next part.

Part D, the Medicare prescription drug benefit, began in 2006. Coverage is provided by private health insurers, with plans differing in costs, copays and list of medications covered or formulary.