route

route manipulates the kernel's IPv4 routing table: which destinations go via which interfaces or gateways. It is part of the legacy net-tools package and has been superseded by ip route.

route -n                         # numeric routing table
route add default gw 10.0.0.1    # add a default route (legacy)
ip route                         # modern equivalent

route never supported IPv6 properly and has been replaced on all modern distributions; it is retained mostly out of habit and for reading older documentation.