IDL: interface defined lang auto generated server skeleton/ client stub

service is collection of methods that can be remotely invoked. client-side implementation involve setting up a connection with the remote server, attaching the client stub with that connection, and invoking the remote method using the client stub.

gRPC over HTTP2, Marshaling is the process of packing parameters and a remote func‐ tion into a message packet that is sent over the network

It has simple, well-defined service interfaces and schema and duplex streaming