This is an excerpt from Dollar Scholar, the Money newsletter where managing editor Julia Glum teaches you the modern money ...

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.

Compound interest allows money to grow exponentially by earning interest on both the initial principal and accumulated interest. A $1,000 deposit at a 4% annual rate grows to $1,040 in one year, then ...