Firewall

A firewall is a security system designed to protect networks and computers from unauthorized access and threats like viruses and malware. It works by filtering incoming and outgoing network traffic based on security rules, allowing only legitimate data through. A firewall can be software, hardware, or a combination of the two.

You can think of a firewall as the bouncer at a digital nightclub. It checks each piece of data trying to get in, and if it looks suspicious, it blocks it from entering. This way, only the good data gets in, while all the troublemakers are kept out.