DMZ - Demilitarized Zone.

A demilitarized zone (DMZ) is an area where
you can place a public server for access by
people you might not trust otherwise.
By isolating a server in a DMZ, you can hide or
remove access to other areas of your network.
You can still access the server using your network,
but others aren’t able to access further network resources.
This can be accomplished using firewalls to isolate
your network.

The easiest way to create a DMZ is to use a firewall
that can transmit in three directions:
to the internal network,
to the external world (Internet),
and to the public information you’re
sharing (the DMZ).