Border Gateway Protocol (BGP) is a network routing protocol to direct network traffic the most efficient path by specifying hop count (and other attributes) for the transmission.
The autonomous systems (AS) that makes up the internet use BGP to direct traffic but BGP can also be used internally. To avoid BGP hijacking, when traffic is rerouted by bad actors or in some cases by mistake, routing public key infrastructure (RPKI) system was created.
More on BGP from Networkworld: BGP: What is border gateway protocol, and how does it work?