The primary function of a network router in computer networking is to direct data packets between different networks. Routers analyze IP addresses to determine the most efficient path for forwarding packets to their destination. They also connect home or office networks to the internet, managing traffic flow between connected devices. Routers often include firewall capabilities, enhancing security by monitoring incoming and outgoing traffic. Moreover, they handle tasks such as network address translation (NAT), which allows multiple devices to share a single public IP address.