gRPC uses Protocol Buffers (protobuf) for data serialization. Protobuf is a binary serialization format developed by Google, which allows efficient and extensible encoding of structured data. It’s important because it ensures that the data structure remains intact during transmission between client and server. This reduces the risk of data corruption or loss. Additionally, protobuf is language-agnostic, enabling gRPC to support multiple programming languages. Furthermore, compared to other formats like JSON or XML, protobuf is more compact and faster, leading to improved performance in network communication.