Your first opportunity to enroll in Original Medicare coverage (Parts A and B) is around the time you turn 65. When you enroll in Original Medicare, you are only enrolling in basic hospital and basic medical health coverage.
After you join Original Medicare, you can apply for optional Medicare health and drug coverage. Plans that provide this health insurance coverage are called Medicare Advantage Plans (Part C) and Medicare Prescription Drug Plans (Part D). Your first opportunity to enroll in these plans is also around the date you turn 65.
If you do not enroll in a Medicare plan around your 65th birthday, there are also designated periods when you can enroll each year.
The period when you can join a Medicare plan is called the "enrollment period.