What does a firewall accomplish?

A firewall is a crucial element in network security, primarily serving as a barrier against unauthorized access to a computer or network. It monitors incoming and outgoing traffic based on predetermined security rules. By doing so, a firewall helps to protect sensitive data from malicious attacks and unauthorized users, effectively preventing intrusions.

Firewalls can be either hardware-based or software-based and work by filtering requests to access data, ensuring that only those that meet specific security criteria are allowed through. This function is vital in safeguarding personal and corporate networks against cyber threats, such as viruses, hackers, and data breaches.

In contrast, the other options relate to different functionalities: speeding up internet connections typically involves optimizing network traffic or utilizing faster hardware, file sharing across networks is about facilitating communication between systems, and managing power consumption pertains to energy efficiency rather than security. Hence, the primary role of a firewall is best encapsulated by its function as a protective barrier against unauthorized access.