A payment rail carries payment messages and supports the transfer or settlement of value through participating institutions or networks. Different rails vary in speed, cost, supported assets, geography, reversibility, identity requirements, and operating hours.
Giving an AI agent access to a payment rail solves only the movement of money. Agentic commerce also needs authorization, limits, compliance, recipient checks, transaction records, and accountability around every request.
ELI5
A payment rail is the system that carries a payment from the sender's side to the receiver's side. It is the transport for the transaction, not the complete set of decisions about whether the payment should happen.
For example, a bank-transfer network can move money after receiving valid instructions. An AI agent still needs separate permission and policy checks before it is allowed to send those instructions.
