Compound interest can help turbocharge your savings and investments, or it can quickly lead to an unruly balance, keeping you stuck in a cycle of debt. Its magic can help you earn more — or owe more.

The effective annual interest rate shows the true yearly cost of borrowing or return on investment, factoring in compounding.

Compound interest is a powerful force for consumers looking to build their savings. It creates a multiplier effect on your money that can help it grow more over time. Knowing how it works and how ...