There are several ways to become eligible for Medicare. Most people will become eligible by aging into the system when they turn 65, but you can also become eligible if you have a long-term disability.
Knowing when to enroll in Medicare is important. If you miss your opportunity to enroll when you first become eligible, you could face costly penalties that stay with you the entire time you have Medicare coverage.
Most people will automatically be enrolled in Medicare Part A when they turn 65, but many will still need to enroll in a Part B plan. All Medicare enrollments happen through Social Security.