If you’re under 65, chances are you don’t know a lot about a program known as Medicare Advantage. But you will be hearing a lot more about it soon. It has become a major front in the growing war that the insurance industry is waging on the Obama Administration’s health reform effort. On Tuesday, the health insurance lobby launched a seven-figure ad campaign in at least a half-dozen states warning: “Congress is proposing over $100 billion in cuts to Medicare Advantage. … Many seniors will see cuts in benefits.”

So what should you know about Medicare Advantage?