A tűzfal is a security system designed to protect computer networks from unauthorized access and cyber threats. 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 traffic based on predetermined security rules, tűzfalak help prevent data breaches and attacks. There are different types of tűzfalak, including hardware and software versions. Hardware tűzfalak are physical devices that sit between a network and its connection to the internet, while software tűzfalak are applications installed on individual computers. Both types work together to enhance network security.