What is the function of firewall?

A firewall is a piece of software or hardware that monitors incoming and outgoing network traffic and decides, based on a set of security rules, whether to allow or block specific data. It acts as a barrier between a trusted internal network (such as a school or home network) and untrusted external networks (such as the internet).

Its main purpose is to prevent unauthorized access, viruses, and malicious attacks from reaching a computer or network, while still allowing legitimate communication to pass through. This protective role places the firewall squarely within the field of cyber security, which covers all the tools and practices used to protect computer systems and data from digital threats and attacks.

A firewall does not provide internet access like a service provider, it is not a browser used to view web pages, and it is not a storage device used to hold data. Confusing it with an internet browser is a common mistake because both deal with internet traffic, but a browser displays content while a firewall filters and controls that traffic for safety.

Exam reminder: whenever a term describes filtering, blocking, or protecting a network from threats, classify it under cyber security.