A hardware firewall is a physical device that protects a network by filtering incoming and outgoing traffic. It acts as a barrier between a trusted internal network and untrusted external networks, such as the Internet. By examining data packets, it can block unauthorized access and prevent potential threats from reaching connected devices. These firewalls can be installed at the network's entry point, often between a modem and a router. They offer various features, including intrusion detection, VPN support, and content filtering. Hardware firewalls are commonly used in both home and business environments to enhance security and maintain network integrity.