The health system in the United States appears to be completely different than ours. Indeed, the american system has always been less social than the french one.
In our country, we couldn't imagine not being able to be supported by a hospital when we are suffering from certain diseases. In the United States, those kind of situations exist.

Indeed, in the USA, some people are not even covered by health insurance.
The poorest people are covered by the state thanks to a system called Medicaid.
The oldest ones and the invalid are also covered by the state, thanks to Medicare.

But most of them are covered by an insurance given by their employer.

The problem is that if you don't have a job, and you are not old or poor enough, you don't have any insurance unless you pay it yourself. In the United States, a lot of people are not poor enough to be helped by the state, and not rich enough to ensure themseves through private organizations.
When those people have health problems (serious disease for example), they can't even be treated or have access to medical care.

The biggest problem in that system appears to be the private insurances, which are overpriced.
That is why the reform Obama wants to apply is supposed to establish new insurance organizations which would compete the private ones. The president wants to create alternative organizations.

Then, an intermediary organization would offer health insurance at affordable prices to the americans who are not covered