An edge router is a networking device that connects a local network to an external network, such as the internet. It is responsible for routing data packets between the local network and the external network, allowing devices on the local network to communicate with devices on the external network. Edge routers typically use routing protocols, such as Border Gateway Protocol (BGP), to exchange routing information with other routers on the internet. They also typically have security features, such as firewall and VPN capabilities, to protect the local network from unauthorized access.