中文：

本金保障是指投资者在进行投资时，保证其投入的本金不会损失的一种机制。简单来说，本金保障就是保护投资者投资本金不受损失。

本金保障机制通常与金融衍生品交易相关。在金融衍生品交易中，投资者需要缴纳一定的保证金来获得交易资格。这个保证金就是保护投资者投资本金的第一道防线。如果投资者的交易出现亏损，保证金账户的资金会减少，但不会低于零。当保证金账户的资金为零时，投资者必须立即追加保证金，否则其交易头寸将会被强行平仓。

除了保证金制度外，一些交易所还会采取其他措施来保障投资者的本金安全。例如，交易所可以设立涨跌停板制度，限制价格的波动幅度，从而降低投资者因市场波动而遭受损失的风险。此外，交易所还可以提供投资者资金结算服务，确保投资者的资金安全和结算的准确性。

总的来说，本金保障是金融衍生品交易中非常重要的一环，它可以帮助投资者降低风险，保护其投资本金不受损失。

英文：

Principal protection refers to a mechanism that guarantees investors will not lose the principal of their investment. In simple terms, principal protection protects investors from losing their investment capital.

Principal protection is typically associated with trading in financial derivatives. In derivative trading, investors must pay a certain amount of margin to obtain trading privileges. This margin is the first line of defense to protect investors' investment capital. If an investor's trading results in losses, the funds in the margin account will decrease, but will not drop below zero. When the funds in the margin account reach zero, investors must immediately deposit additional margin, otherwise their trading positions will be forcibly liquidated.

In addition to the margin system, some exchanges also take other measures to protect investors' capital security. For example, the exchange can establish a price limit system to restrict the price fluctuation range, thereby reducing the risk of investors suffering losses due to market fluctuations. In addition, the exchange can also provide investors with fund settlement services to ensure the safety of investors' funds and the accuracy of settlement.

Overall, principal protection is a very important part of derivative trading, which can help investors reduce risks and protect their investment capital from losses.