A DMZ, or demilitarized zone, is a physical or logical subnetwork that contains and exposes an organization's external-facing services to an untrusted network, usually the internet. The purpose of a DMZ is to add an additional layer of security to an organization's local area network (LAN): an external attacker only has direct access to equipment in the DMZ, rather than any other part of the network. The term 'neutral zone' refers to the fact that the DMZ is separated from both the internal network and the untrusted network, which helps prevent attackers from directly accessing internal servers and data. It is not a file integrity monitoring mechanism, does not serve as a proxy, and typically does not include sensitive internal servers like database servers, which are kept inside the trusted network for security reasons123.
References:
* Fortinet's explanation of a DMZ network1.
* EC-Council's Certified Network Defender (CND) course outline2.
* An article on strengthening network security with DMZ3.