Border Gateway Protocol (BGP)
BGP is the routing protocol that networks use to exchange information about which IP addresses they can reach, holding the internet together.
What is Border Gateway Protocol (BGP)?
Each network, or autonomous system, announces the address prefixes it can deliver traffic to, and BGP chooses paths between networks based on policy, not just distance. External BGP (eBGP) runs between different networks; internal BGP (iBGP) distributes those routes within one network, often using route reflectors so that every router does not need a session with every other.