What is compound interest?

Compound interest refers to the process of earning interest on both the initial principal and any interest that has already been accrued over previous periods. This means that as interest accumulates, it adds to the principal, leading to potentially exponential growth of the investment or savings over time. The more frequently the interest is compounded, the greater the effect this has on the total amount, as each period's interest calculation considers the total balance that includes previous interest earned.

This is distinct from simple interest, which is calculated solely on the original principal amount throughout the time period. Compound interest can occur at different intervals, such as annually, semi-annually, quarterly, or monthly, but what defines it is that it includes interest on the accrued interest, leading to a faster accumulation of wealth.