If you've got several debts and you're finally ready to attack them, you'll run into two competing plans almost immediately. The avalanche says pay the highest interest rate first. The snowball says pay the smallest balance first. People argue about this like it's theology. It isn't. Both work, and the difference between them is smaller than the argument suggests.
The avalanche wins on paper every time. Interest is the cost of carrying debt, so killing the most expensive debt first saves the most money. If you're the kind of person who builds a spreadsheet and sticks to the plan for three years, take the avalanche and don't look back.
The snowball wins on something the spreadsheet doesn't measure. Knocking out a small balance in two months gives you a closed account, a freed-up payment, and proof that this can actually work. That momentum keeps people in the game. And the fair criticism of the avalanche is exactly this: a mathematically perfect plan you abandon in month four loses to an imperfect plan you finish.
So pick by knowing yourself. If unfinished projects litter your past, take the snowball. If watching interest pile up makes your jaw tight, take the avalanche. The order matters less than the follow-through, because either plan beats the default plan, which is minimum payments forever.
There's also a third approach: putting your monthly cash flow itself to work against the debt, using a line of credit as the hub. That's the whole subject over at Dynamic Banking, and it pairs fine with either payoff order. Whatever you choose, the first step is the same. List every debt, every rate, every minimum, on one page. You can't order a list you haven't made. More basics live on the Learn page.