Pronounced as separate letters, DMZ is short for demilitarized zone, a computer or small subnetwork that sits between a trusted internal network, such as a corporate private LAN, and an untrusted external network, such as the public Internet.
Typically, the DMZ contains devices accessible to Internet traffic, such as Web (HTTP ) servers, FTP servers, SMTP (e-mail) servers and DNS servers.
The phrase demilitarized zone comes from military use, meaning a buffer area between two enemies.