Credit cards can be a useful part of your financial toolbox. Along with enabling you to purchase items now and pay for them later, credit cards can also help you build your credit score. But don’t start filling out that application until you have a good understanding of how credit cards work. It’s easy to sign on the dotted line, but it isn’t as easy to understand the fine print that weaves its way into credit card contracts. Before signing up, here’s what to keep in mind about hidden (and potentially deceptive) credit card terms and conditions.