A credit score is a numerical summary of your credit history — in the U.S., FICO scores range from 300 to 850. Lenders use it to estimate the risk that you won’t repay, which directly affects your approval odds and the interest rates you’re offered.
The largest factors are payment history and credit utilization (how much of your available credit you use), followed by length of history, new credit and credit mix. Higher scores can save tens of thousands of dollars in interest over a lifetime of borrowing.