Google’s Answer
A payment scheme is a body that sets the rules and technical standards for the execution of payment transactions using the underlying payment systems. It complies with regulatory aspects governing payment schemes and systems and has access criteria and an application process for joining.
Our Answer
A payment scheme is a defined protocol of transferring messages of value between two parties. It could be a card payment scheme such as VISA, MasterCard or AMEX, bank payment scheme like Faster payments, ACH or SWIFT or a modern crypto payment system like block chain.