What is the debt avalanche method?

The debt avalanche method pays minimum payments on all debts, then directs all extra money toward the debt with the highest interest rate first. Once that debt is paid off, you roll that payment to the next highest-rate debt. It is mathematically optimal — you pay the least total interest over time. The downside is that high-balance, high-rate debts can take a long time to pay off, testing your motivation.