Group Health Insurance
Group Health Insurance is the kind you are eligible for when you work for a company that buys coverage as a benefit for employees.
The employer buys the coverage from an insurance company and pays part of the premium cost, usually just for the employee.
The employee's family is also eligible for coverage, but usually, the employer is not paying any part of their premium.
With group coverage, it doesn't matter what your health status is. It only matters that you are a group member.
This is the primary difference between group and Individual Health Insurance, where your health status at the time of application is very important.
With group coverage, you must join when you first become eligible or wait till the next annual Open Enrollment Period. Why? Because, if they let you join at anytime, nobody would sign up until they got sick.
An Introduction to the Basics of Medicare a short video