A firewall controls network traffic based on security rules.
It can allow normal business communication while blocking connections that are not permitted.
Businesses may have firewalls on individual computers, at the edge of the network, or both.
A firewall is not a complete security system. It cannot stop every phishing email or prevent an employee from giving away a password.
However, it plays an important role by limiting how systems communicate.
Modern business firewalls may also include web filtering, intrusion prevention, VPN services, and other security features.
The best firewall is one that is properly configured and monitored. A powerful firewall with weak rules can still leave a business exposed.
Network security works best when it is combined with identity protection, endpoint security, patching, and backups.