本金一般是指借贷行为中，由负债方所借贷的原始资金总额，其后的债务利息将以此为基准进行计算。对于提供借贷一方，也就是「投资」的行为中，本金指的是投资人所投入的资金总额。

• 负债
• 贷款
• 利息计算

The principal balance, in regard to a mortgage or other debt instrument, is the amount due and owing to satisfy the payoff of the underlying obligation, less interest or other charges.

Amortized mortgage loans automatically pay a portion of each monthly payment to the principal balance, with the rest being paid as interest.