Firewall

A firewall is a network security device or software that monitors, filters, and controls incoming and outgoing network traffic based on security rules. Firewalls act as a barrier between trusted internal networks and untrusted external networks. Types include packet-filtering, stateful inspection, proxy, and next-generation firewalls (NGFW). Modern firewalls incorporate intrusion prevention, application awareness, and threat intelligence. Both hardware and software firewalls are essential components of network security architecture.