There are many versions, or "parts," of Medicare. Which one you're on determines your benefits, who pays for them, and related things.
                        
A Medicare Advantage plan, also known as "Medicare Part C," is one that is run by private insurers that have been authorized by Medicare. It combines Medicare Parts A and B into a unified plan. Like health insurance for younger people, it comes with variations like HMO and PPO.
                        
One of the reasons to sign up for this type of plan is convenience. It covers everything that Medicare normally would, but streamlines things so you don't have to keep track of different parts, insurers, and other details. You can expect to get coverage for doctor and hospital visits, prescription costs, vision, dental, and more.
                        
Since there are variations, such as the Medicare Advantage PPO plan, you will need to do some thinking to decide on which one to sign up for. Typically, with PPO (a Preferred Provider Organization), you have a choice of fully-covered in-network doctors and a full selection of out-of-network doctors.
                        
The coverage for in-network doctors and hospitals is usually much greater than it is for out-of-network providers. Therefore, it is important to make sure that all of your favorite healthcare providers are in-network for the plan you're considering. It's usually worth it to get a more-expensive plan if that's what it takes to ensure that your favorite providers are eligible for in-network pricing.
                        
Most people prefer PPOs to HMOs because the latter are far more restrictive. An HMO usually won't cover out-of-network providers at all. This is a hassle in any case, but if you're hospitalized, it's especially negative. Hospitals often have outside professionals join in on your health care, and these might not all be in-network. Choosing a PPO limits your financial liability for their services.