Remote Procedure Call (RCP) is a communication protocol that allows applications to execute functions on a remote server as if they were local. In the context of blockchain infrastructure, Electrum RPC is a persistent, stateful protocol designed for real-time blockchain monitoring. Unlike request-response protocols, RPC maintains long-lived connections that enable applications to subscribe to blockchain events and receive instant push notifications when something happens, such as when an address receives a payment or a new block is found. Electrum RPC has been powering Bitcoin wallets for over a decade and is available across all Blockstream Explorer API tiers with production-grade rate limits for high-volume applications.