Border Gateway Protocol (BGP) is a standardized exterior gateway protocol used to exchange routing information between different networks on the internet. It helps determine the best paths for data to travel across multiple autonomous systems, which are large networks or groups of networks managed by different organizations. BGP operates by using a path vector mechanism, where each router maintains a table of network paths. This allows routers to make informed decisions about the most efficient routes for data packets, ensuring reliable and efficient communication across the vast and complex structure of the internet.