For many Americans, navigating the maze of health insurance options—from employer-based plans to individual policies—can be dizzying. Much of that changes at 65. That’s when individuals generally are eligible for Medicare, which covers routine health care expenses such as visits to doctors and prescription drugs. But the program doesn't cover everything. Here is a breakdown of how Medicare works—and your coverage options for filling in the gaps.   Inside Medicare  Medicare comprises four parts that cover different health care services and carry various financial obligations. People who are already receiving [...]