Negative interest rates are when deposit interest rates are below zero.

Normally, the depository bank will pay a certain amount of interest to the depositor to encourage deposits.

But negative interest rates mean depositors pay a fee to keep their money in a bank.

Several aspects of negative interest rates will be explained in detail below.

First, the impact of negative interest rates on depositors is the need to pay interest rate costs.

Under normal circumstances, depositors can earn interest by depositing funds in a bank, which increases the value of the funds.

However, during periods of negative interest rates, depositors need to pay certain fees to banks.

This is due to the central bank adopting negative interest rate policies to stimulate the economy and encourage financial institutions to expand lending and investment, thereby promoting economic growth.

Secondly, the impact of negative interest rates on banks is a challenge to their profitability and business models.

Banks usually obtain funds by taking deposits and make profits by lending to borrowers at higher interest rates.

However, in a negative interest rate environment, banks need to pay more fees to depositors, and loan interest rates are also subject to downward pressure, causing banks' net interest margins to shrink and adversely affecting their business models.

In addition, negative interest rates will also have a series of impacts on the entire economic system.

First, negative interest rates encourage borrowing and investment, which can stimulate economic growth.

Secondly, negative interest rates can reduce corporate debt burdens, promote corporate financing, and increase production and employment.

However, negative interest rates may also cause consumers to worry about the future, inhibit consumption and savings, and affect economic stability.

To sum up, negative interest rates mean that depositors need to pay deposit fees to banks, which poses a challenge to banks’ profitability and business models, and at the same time has an impact on the economic system.

Negative interest rate policy is a means adopted by the central bank to stimulate economic growth, but it will also face many challenges and impacts during the implementation process.

Extended information: Negative interest rate policy was first implemented by the Riksbank and has been adopted in Japan, Europe and other places.

The implementation of negative interest rates is mainly to deal with problems such as weak economic growth and deflation.

Since negative interest rates have a greater impact on financial institutions and the economic system, their implementation generally needs to be combined with other monetary policies and economic policies.

Although negative interest rate policy has its positive side, there are also negative impacts and risks that need to be carefully considered and evaluated.

Please note that the above extended information is not part of the answer and is only used to supplement the explanation of the question.