route
also: routing entry, routing rule, default gateway
A route is a rule that determines how network packets are forwarded from a source to a destination based on the target IP address. The routing table stores these rules, and the kernel uses them to decide which network interface to send packets through.
In networking, a route is a mapping that tells your system how to reach a specific network or host. Each route specifies a destination (IP address or network), a gateway or interface to use, and optionally a metric indicating priority. The kernel's routing table contains all active routes and is consulted whenever a packet needs to be sent.
Routes can be static (manually configured and persistent) or dynamic (learned automatically via routing protocols). For example, a route might say "to reach 192.168.1.0/24, send packets out eth0" or "to reach the internet, forward packets to the gateway 10.0.0.1".
You can view routes with route -n or ip route show, and add them with commands like ip route add 192.168.100.0/24 via 10.0.0.1. The default route (0.0.0.0/0) handles packets destined for networks without a specific matching route, typically pointing to your ISP's gateway.