What Do All the Numbers on Your Credit Card Mean?S

What Do All the Numbers on Your Credit Card Mean?S

I always wondered how credit card companies came up with the digits on my Visa and AmEx. Random chance? Geographical location? Spending habits? Turns out all credit card companies follow the same set of rules. Here's what the numbers mean:

I also didn't know that there was a simple method to see if a credit card was fake or not. Smart, those credit card companies are. [Mint]