Now that the individual mandate has been upheld, it's probably time to get serious about understanding what it is. The most common way the mandate has been described in the mass media is the way Jan Crawford describes it in her CBS piece on the Chief Justice's change of heart/mind about the law -- "It requires individuals to buy insurance or pay a penalty" -- which certainly suggests that when fully implemented the law will impose a direct new cost on everyone. Not true. If, for example, you are already covered by your employer's insurance or Medicare, you don't have to buy additional insurance. You can read the 907-page act (PDF) to understand the exceptions (something that even Congress didn't do before voting), or, you can check out this chart from the Kaiser Family Foundation that lays out in one page how it works.
Note: I have not actually read all 907 pages to verify the information in the chart, but have cross-referenced it with other sources.