What is a firewall?

A firewall is fundamentally a security device designed to monitor and control the flow of incoming and outgoing network traffic based on predetermined security rules. By acting as a barrier between a trusted internal network and untrusted external networks, such as the internet, it effectively prevents unauthorized access while allowing legitimate communication. This is essential for protecting systems and data from cyber threats such as intrusions, viruses, and other malicious activities.

Firewalls may be implemented as hardware devices, software applications, or a combination of both, and they play a crucial role in enforcing security policies. Through various techniques, such as packet filtering, stateful inspection, and proxy service, firewalls help to ensure that only permissible data traffic is allowed, thereby safeguarding the integrity and confidentiality of networked systems.

Understanding the primary function of a firewall in the context of network security is essential for recognizing its value in protecting digital infrastructure.