Definition
A Firewall is a security mechanism that controls network traffic according to defined rules to protect systems and Assets from unauthorised communication.
Human Explanation
A Firewall decides which network connections are allowed and which should be blocked.
Why it Matters
A properly configured Firewall limits unauthorised access and reduces the Attack Surface.
Conceptual Boundary
A Firewall does not provide complete network security. It is one element of Security Architecture and must work with other protective mechanisms.
Practical Perspective
The most effective Firewall has rules that are reviewed regularly and reflect the organisation's actual needs.