What is the main purpose of a firewall in computer networks?

A firewall serves as a critical security measure in computer networks, with the primary purpose being to protect against unauthorized access. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet. By monitoring and controlling incoming and outgoing network traffic based on predetermined security rules, a firewall helps to prevent unauthorized users from gaining access to sensitive data and systems within a private network.

The technology can filter traffic based on various criteria, including IP addresses, port numbers, and protocols. This level of control is essential for safeguarding sensitive information and ensuring that only legitimate users can connect to the network, thereby reducing the risk of cyber threats such as hacking attempts, malware, and data breaches.

Other choices do not accurately represent the core function of a firewall. Enhancing internet speed, increasing storage capacity, or improving graphics performance are related to different aspects of computer and network management and do not fall under the purview of a firewall's capabilities.