gRPC - Remote Procedure Calls are not new, but gRPC (developed from Google around 2015) provides a very restricted interface for passing data between applications - binary compressed data for performance, has a wide adoption on many platforms.  Why use it? why is it different from SOAP or REST (or GraphQL even!).  Have a listen to find out more!

Here are a few links that will help take the gRPC subject further if you wish:

A great overview from Wikipedia: https://en.wikipedia.org/wiki/GRPC
Bit more depth here with some examples too: https://grpc.io/docs/what-is-grpc/core-concepts/
If you don't want to read, then the MSDN Channel 9 peeps can help: https://channel9.msdn.com/Shows/On-NET/ASPNET-Core-Series-High-performance-requests-with-gRPC

Get full access to Just Five Mins! at www.justfivemins.com/subscribe