Unified Payments Interface (UPI) is a way to send money from one bank account to another using your phone. It is like making a transfer at the bank, but faster and easier. With UPI, you do not need to know the other person's bank details like their account number or IFSC code. Instead, you can just send them money with their phone number or a different UPI ID. All of this happens within just a few seconds, making it much easier to send or receive money.