The RPC (Remote Procedure Call) mechanism allows an application to seamlessly invoke remote procedures, as if these procedures were executed locally.
There are two main implementations of the RPC mechanism:
MSRPC is the Microsoft implementation of the DCE RPC mechanism. In particular, Microsoft added new transport protocols for DCE RPC, in particular the ncacn_np transport, which use named pipes carried into the SMB protocol.
For an interesting story of Windows and how Microsoft chose to implement DCE RPC, see A brief history of Windows .