In a microservices architecture, gRPC can be used to allow microservices to communicate with each other efficiently and securely.
Each microservice can implement a gRPC server that exposes a set of methods that can be called by other microservices.
The methods can be defined in a Protocol Buffer service definition file, which specifies the input and output types for each method.
The microservices can then use a gRPC client to call the methods exposed by other microservices.