https://grpc.io/docs/what-is-grpc/introduction/
- framework for building APIs that connect services, using HTTP/2 for transport and Protobuf for data serialization
- good for microservices, mobile apps, and DS due to speed
- bi-directional streaming
- allows client app to directly call method on a server app
- client has stub that provides same methods as server, which implements an interface and runs a gRPC server to handle client calls