Explanation: India Stack is the collective name of a set of commonly used digital public infrastructure (DPIs) in India.

• It consists of three different layers — unique identity (Aadhaar), complimentary payments systems (Unified Payments Interface, Aadhaar Payments Bridge, Aadhaar Enabled Payment Service), and data exchange (DigiLocker and Account Aggregator).
• Together they enable online, paperless, cashless, and privacy-respecting digital access to a variety of public and private services, a working paper titled ‘Stacking up the Benefits: Lessons from India’s Digital Journey’ said.

Source: https://www.outlookindia.com/business/india-s-world-class-digital-infra-worth-emulating-by-many-nations-imf-paper-news-276531