Answer : 1. "Unified Payment Interface"
Explanation :

1. UPI (Unified Payments Interface): UPI is a mobile-based payment system that allows users to transfer money from their bank accounts to any other bank account instantly and securely.

2. As a UPI user, you have to create a unique identifier called UPI ID. It is linked to your bank account. With its help, money can be easily sent and received from the bank account. For this, you do not need to share your account number or other information.