1. On the Internet, BGP is used between ISPs in order to communicate routers. For example, imagine that the ALICE ISP needs to reach the BOB ISP. However, ALICE is not directly connected to BOB. ALICE therefore must figure out which ISP should be used to send traffic to BOB. It is through the use of BGP that such information is discovered. The name "border" comes from the fact that ISPs use BGP only on their borders (in contrast, they would use some other protocol (like OSPF) inside their networks). Key point: BGP can be subverted in many ways. BGP is generally unauthenticated, and rogue ISPs can play havoc. From Hacking-Lexicon