A demilitarized zone is also known as a DMZ. It is also known as a firewall setting that separates LAN of an organization from the external network.
DMZ makes certain servers available to everyone while keeping the internal LAN access private and accessible to only authorized people.
So, a DMZ is between the internet and the firewall. To explain it a bit easier, The LAN is where anybody can search in it.
For example, if you have a website and you put it in the DMZ, then nobody outside can find or search it up. But if it is in the LAN than anybody outside can look and search it up.
