RPC (Remote Procedure Call) is a communication protocol that allows a service to invoke procedures on a remote server as if they were local functions. Unlike REST, which focuses on resource-based interactions using URLs, RPC emphasizes procedure calls. An RPC request typically includes the JSON-RPC version, method name, parameters, and a request ID. It's widely used in microservices, IoT, blockchain, and real-time applications. Popular RPC implementations include gRPC (for cloud-native apps), JSON-RPC (common in blockchain), XML-RPC (older systems), and SOAP (web service protocol), supporting various data formats and transfer protocols.