Imagine you’re about to sign a lease on your dream apartment, only to have the landlord hesitate when they see a three-digit number on your application. That little sequence—your credit score—can open doors to the best interest rates or slam them shut, forcing you into a high-cost world of fees and higher payments. But what exactly is a credit score, and why does it wield so much power over your financial give life?

Nowadays, it seems like even the smallest items are overpriced. If you own a vehicle, you’ve likely experienced the rising gas prices...