In IT, a firewall is a network security device that monitors and controls incoming and outgoing network traffic, blocking unauthorized access and protecting against cyber threats based on predefined security rules. Firewalls act as a barrier between a network and external sources, like the internet, or between different parts of a network. Firewalls can be hardware (physical devices) or software (programs running on a computer or server). Firewalls examine network traffic, packets, and decide whether to allow or block them based on rules that specify things like source and destination IP addresses, port numbers, and application types. Learn more: https://en.wikipedia.org/wiki/Firewall