There are four basic items of information in such a table A destination IP address. A gateway IP address. This will be the same as the destination IP address for directly connected destinations. Various flags usually displayed as U, G, H and sometimes D and M. U means the route is up. G means the route is via a gateway.
H means the destination address is a host address as distinct from a network address.
The physical interface identification. A general purpose host may have connections to at most two or three networks and a correspondingly simple table. Such autonomous systems are usually run by a single organisation such as a company or university. Within an AS, routers communicate with each other using one of several possible intra-domain routing protocols also known as interior gateway protocols. ASs are connected via gateways, these exchange information using inter domain routing protocol also known as exterior gateway protocols.