Definition
Debt snowball
The debt snowball is a repayment method where you clear your smallest balance first while paying minimums on everything else, then roll the freed-up payment onto the next smallest. The appeal is momentum, since early wins are quick and visible.
The debt avalanche instead targets the highest interest rate first, which normally costs less in total but takes longer to show progress. Neither approach is wrong, and the one you can keep up with is usually the better choice.