President Obama signed the Affordable Care Act, otherwise known as Obamacare into law on March 23, 2010. The requirement that people have health insurance begins on January 1, 2014. If you don't have insurance, you will be required to pay a penalty.
There are a few exceptions to the mandate. You can go 3 months without coverage. If your income is low enough that you do not have to file taxes or the cheapest plan is more than 8% of your income you are not required to purchase coverage. The penalty for being uninsured in 2014 is $95 or 1% of your income, whichever is more. The penalty will increase every year until it hits $695 or 2.5% of your income.
If your income is low enough to exempt you, you may qualify for government medical assistance. If you are under age 65 and purchase your own health insurance and are not covered by your employer, you will be eligible for tax credits.
As a result of the Affordable Care Act, insurance companies will no longer be able to discriminate against people with preexisting conditions. Insurers will also be prohibited from imposing benefit caps that would limit the amount of coverage that people who require constant medical will receive.