What function does a firewall serve in network security?

A firewall plays a crucial role in network security by controlling incoming and outgoing network traffic. This involves analyzing data packets and making decisions based on predetermined security rules. By establishing a barrier between trusted internal networks and untrusted external networks, firewalls help prevent unauthorized access and protect sensitive information from threats such as hackers, viruses, and other malicious activities.

The core function of a firewall is to filter traffic; it can allow or block data packets based on specific criteria, ensuring only legitimate traffic is permitted while suspicious or harmful data is denied access. This capability is essential in safeguarding network integrity and preserving the confidentiality and availability of data.

In contrast, the other options do not accurately capture the primary function of a firewall. For instance, monitoring social media usage is not within the scope of a firewall's capabilities; instead, this would typically involve web filtering and user monitoring solutions. Managing email accounts relates to email services rather than the foundational security role of a firewall. Lastly, while internet speed can be influenced by network management practices, firewalls do not inherently serve to accelerate internet speed; their purpose is security-focused rather than performance-oriented.