What are interest rates?

Interest rates represent the cost of borrowing money, expressed as a percentage of the principal amount borrowed over a specific period. When a borrower takes out a loan, the lender charges an interest rate, which compensates the lender for the risk of lending and for the opportunity cost of the funds used. This charge is crucial for both lenders and borrowers, as it affects the overall cost of financing for individuals and businesses alike.

Understanding that interest rates can vary based on factors such as the borrower's creditworthiness, the economic environment, and the type of loan is essential. For instance, higher interest rates can reflect increased risk or inflation expectations, while lower rates might indicate a competitive lending environment or stronger economic conditions.

The other options refer to different financial concepts that do not directly relate to what interest rates are. The total amount borrowed, for instance, is the principal, while currency exchange rates deal with the value of money between different currencies. Fees associated with banking services pertain to transactional or operational costs rather than the concept of borrowing money itself. Therefore, the definition of interest rates aligns clearly with the notion of a charge applied for the use of borrowed money, making it the correct answer.