What is a firewall used for in a network?

A firewall is used in a network to monitor and control incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet, to prevent unauthorized access, data breaches, and cyber attacks. Firewalls can also block malicious traffic, filter out unwanted content, and protect against various types of cyber threats, such as malware, viruses, and hacking attempts.