Banks loan money to customers and charge interest, but there's more to the story.Have you ever wondered how banks make their money? While the banking business itself can be quite complex, the ways in which banks make money can be surprisingly easy to understand. Here's a quick rundown of the two main ways banks make their money and some key details to know about each one. Source: Getty ImagesHow banks make moneyAt their core, banks make money in two main ways -- commercial banking a...