What is Firewall?

Firewall, explained

A firewall acts as a checkpoint between a trusted network, such as a company's internal systems, and an untrusted one, like the internet. It inspects data packets and decides whether to let them through based on factors like source, destination, port, and protocol.

Firewalls can be hardware appliances, software on individual computers, or cloud services. Next-generation firewalls add deeper inspection, recognizing specific applications, detecting intrusion attempts, and filtering malicious content. Web application firewalls focus on protecting websites from attacks like SQL injection and cross-site scripting. Firewalls remain essential, but because users and data now live far beyond the office network, they are one layer within broader strategies such as zero trust.