Learn what compound interest is, how it’s calculated—from annual rates to continuous compounding—and why it’s powerful for savings (and dangerous for debt).

An annuity is an insurance contract you purchase to receive payments for a specific period, such as 30 years, or for the rest of your life. By applying a mathematical formula consisting of variables ...

is—it’s effectively a percentage of an amount over a year. If your savings account earns you a 0.05% interest per year (which is a REALLY terrible interest rate, honestly), you earn $5 in interest for ...