gRPC is an open-source high-performance remote procedure call (RPC) framework developed by Google. It enables clients and servers to communicate with each other efficiently and securely over various transport protocols, such as HTTP/2, TCP, and UDP. gRPC supports multiple programming languages and platforms, including Python, Java, C++, and JavaScript, making it a versatile tool for building distributed systems. Mastery of gRPC requires proficiency in programming languages, networking, and distributed systems design.