Years ago, when I was learning my first big boy job, a project manager was coaching me on a bad habit I had at the time.
PM: (Bad habit) is like going shopping, when you don't know what your credit limit is. You wouldn't do that, would you?
Me: What's a credit limit? (Asking honestly, I was young and didn't know things)
PM: WHAT? You ACTUALLY don't know your credit limit?
Me (concerned): Uhhh, no...is that important?
Then he told me all about how credit cards work and how important it is to find out my credit limit RIGHT NOW and make sure I never go over the limit on my credit card, or something REALLY BAD will happen. When I got back to my desk, I frantically checked my bank account online and couldn't find this credit limit thing anywhere so I called their customer service, where a nice lady patiently explained to clueless me that my debit card is not the same thing as a credit card.