When you borrow money from a bank, you pay interest.
Interest is really a fee charged for borrowing the money,
it is a percentage charged on the principle amount for a period of a year - usually.

\(
S = P \left(1 + \dfrac{j}{m}\right)^{mt} \ \
\)
where:

\( S \) | is value after \( t \) periods |

\( P \) | is principal amount (initial investment) |

\( t \) | is number of years the money is borrowed for |

\( j \) | is annual nominal interest rate (not reflecting the compounding) |

\( m \) | is number of times the interest is compounded per year |