What is a firewall, and how does it function?

A firewall is fundamentally a network security device designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. It serves as a barrier between a trusted internal network and untrusted external networks, such as the Internet. By analyzing the data packets that attempt to enter or leave the network, it can allow or block traffic based on established security protocols.

The primary function of a firewall is to prevent unauthorized access while allowing legitimate communication. It can configure various rules to specify what type of traffic to permit or deny. This helps protect against threats such as unauthorized access attempts, intrusion attempts, and other malicious activities that could compromise network security.

The other options do not accurately capture the core function of a firewall. While malware protection (mentioned in the first option) is important, it is not the primary role of a firewall but rather falls under the function of antivirus software. The choice regarding data backup refers to a different aspect of data security entirely and does not pertain to the monitoring of network traffic. Lastly, tracking user behavior is typically handled by different tools focused on analytics or monitoring rather than core network security devices.