The term "firewall" originally referred to fireproof walls that were designed to prevent the spread of fire from one room or building to the next. They were typically made of brick, steel, or another type of inflammable material that would effectively limit the spread of the fire. In the IT world, firewalls do not involve any fire or pyrotechnics, but they serve a similar purpose. A computer firewall limits the data that can pass through it and protects a networked server or client machine from damage by unauthorized users.


Updated: October 26, 2007