The cash rate is the interest rate that financial institutions pay to borrow or charge to lend funds in the money market on an overnight basis. This measure is also known as the interbank overnight rate
The cash rate is consequently very important, because of its strong relationship to market interest rates. For example, mortgage and business loans rates tend to move in line with movements in the cash rate.
The Reserve Bank’s influence over the cash rate comes from the changes in the banks demand for exchange settlement funds. For example, payments to the banks by the Reserve Bank add to exchange settlement funds.