BGP is a path-vector protocol. Therefore, BGP routes contain…
- the destination network
- the next-hop router
- the AS Path
BGP is different from Interior Gateway Routing Protocols (IGPs) because it is policy-based; the AS administrator modifies policy attributes that are shared with other ISPs/ASNs through external BGP (eBGP). The BGP best-path algorithm determines the best AS Path to route through for a particular destination.
The main differentiator between IGPs and BGP is that the former is based on speed and finding the fastest route to a destination, whereas BGP is solely focused on routing policy to control traffic flow through AS Attributes.
Stuck-in-Active: Journal of an IT-Network Administrator 