A firewall is a barrier between your device and the internet that monitors and filters network traffic. It blocks unauthorized access while allowing safe data through. Firewalls come in software (on devices) or hardware (on routers) forms. They use rules to permit or deny traffic based on source, destination, or content.

For example, a firewall might block a known malicious IP address or a suspicious app trying to send data out. Firewalls help prevent hackers, viruses, and intrusions from reaching your system. As part of a layered security strategy, firewalls work with antivirus and secure practices to protect users.