What banks pay their customers interest on the money in their accounts for what reason?

Banks pay interest on customer deposits as a way to attract and retain customers, encouraging them to keep their money in the bank rather than withdrawing it or investing elsewhere. This interest is often a small percentage of the total deposit and serves as a reward for customers while the bank uses those funds to make loans and investments, generating profit. The interest paid helps maintain customer loyalty and enhances the bank's competitiveness in the financial market.