What is melamine? Is it in my milk?

Every few months the media seems to dig up a new quality control issue with Chinese products. Many of these are largely just typical media fear factoring, but the recent "melamine in milk" debacle is very real and very wide-spanning.

If you're like us, you probably gasped in horror when it was reported that virtually every major distributor's milk in China was tainted with melamine. Then, again if you're like us, you stopped and said, "wait, what exactly is melamine?"