Types of Debt: A Plain-Language Glossary
Last updated: August 5, 2026
Every calculator on this site asks for a balance, an APR, and a minimum payment, and uses words like principal and amortization without ever stopping to define them. This page does that, once, in plain language, with links back to the tools that actually use each term.
Terms
- Principal
- The amount you actually borrowed or currently owe, before interest. Every payment you make is split between reducing the principal and covering interest that has already accrued; a payment only starts shrinking your balance meaningfully once it exceeds that month's interest.
- APR (annual percentage rate)
- The yearly cost of borrowing, expressed as a percentage. It is the number every calculator on this site asks for. Divide it by 12 for a rough monthly rate, though many card issuers actually compound daily rather than monthly; see the About page for the exact difference.
- Minimum payment
- The smallest amount your lender requires each billing cycle to keep the account in good standing. Paying only the minimum on a revolving balance can take years and cost far more in interest than the original amount borrowed, which is the entire reason the calculators on this site exist.
- Amortization
- The process of paying down a loan through scheduled payments that cover interest first and principal second, with the mix shifting toward principal over time as the balance shrinks. A fixed-rate installment loan, like a personal loan or a consolidation loan, amortizes on a set schedule; a credit card does not, since your payment and balance can both change month to month.
- Secured debt
- Debt backed by collateral the lender can seize if you stop paying, such as a mortgage secured by the house or an auto loan secured by the car. Secured debt usually carries a lower interest rate than unsecured debt because the lender's risk is lower.
- Unsecured debt
- Debt with no specific asset backing it, such as most credit cards, medical bills, and personal loans. If you stop paying, the lender cannot automatically seize a specific possession; instead, it typically pursues collections, and eventually may sue for a judgment.
- Revolving debt
- A credit line you can borrow against, repay, and borrow against again, up to a limit, with no fixed end date. Credit cards and lines of credit are revolving. Because the balance and minimum payment move with what you owe, revolving debt tends to feel more open-ended than installment debt.
- Installment debt
- A loan for a fixed amount, repaid in a fixed number of scheduled payments over a set term. Personal loans, auto loans, student loans, and consolidation loans are installment debt. Once the term ends and the final payment clears, the loan is gone; there is no revolving balance to manage afterward.
- Debt snowball
- A payoff strategy that targets the smallest balance first, regardless of interest rate, to build momentum from early wins. Covered in depth on the debt snowball calculator.
- Debt avalanche
- A payoff strategy that targets the highest interest rate first, which minimizes total interest paid across all your debts. Covered in depth on the debt avalanche calculator.
- Debt-to-income ratio
- Your total monthly debt payments divided by your gross monthly income, expressed as a percentage. Lenders use it to judge how much additional debt you can reasonably take on; it is not the same thing as your credit score, which looks backward at repayment history rather than forward at capacity.
- Debt consolidation
- Combining several debts into one new loan, ideally at a lower interest rate than the blended rate of what you currently owe. It simplifies payments to one bill a month, but only saves money if the new rate is genuinely lower; see the debt consolidation calculator for the actual arithmetic on your own numbers.
Where these terms show up
Balance, APR and minimum payment are the three inputs on every multi-debt calculator on this site: the debt payoff calculator, the snowball and avalanche calculators, and the side by side comparison. Principal and amortization matter most on installment debt, which is exactly what the credit card payoff calculator and the consolidation calculator model directly.
Frequently asked questions
Does it matter which type of debt I pay off first?
Not for the math itself, since both secured and unsecured debts accrue interest the same way in the calculators here. It matters for the consequence of falling behind: miss payments on a secured debt and the lender can take the collateral, which is why most people prioritize a mortgage or car payment even over a higher-rate credit card. The snowball and avalanche calculators do not know which debts are secured; that judgment call is yours to layer on top of the math.
Why does it matter whether my debt is revolving or installment?
Mainly because of what an extra payment means for each. On an installment loan, paying extra shortens the loan; the payment stays the same but the payoff date moves up. On revolving debt, your minimum shrinks as the balance shrinks unless you keep paying the original amount on purpose, which is exactly what the rollover setting on the debt payoff calculator controls.
Why does APR matter more on some debts than others?
Because interest compounds on whatever principal remains, a high APR on a large, slow-shrinking balance costs far more than the same APR on a small one. That is exactly why the avalanche strategy, which targets the highest rate first, tends to save money: in the worked example on the debt payoff calculator, it saves $34.07 against paying the smallest balance first instead, purely from the ordering.
Is a debt consolidation loan the same as a balance transfer card?
No. A consolidation loan is a fixed-rate installment loan for a set term. A balance transfer moves a balance to a new credit card, usually under a promotional 0% APR window that later expires and reverts to a standard, often high, revolving rate. Read the promotional terms carefully before assuming a balance transfer behaves like a consolidation loan.
Sources
- Consumer Financial Protection Bureau. Credit Reports and Scores resources. Checked 2026-08-03.
- Consumer Financial Protection Bureau. Debt collection resources. Checked 2026-08-03.