Defense structure is a term used to describe a structure built for the purpose of defending an area from attack. A FORT is a type of defense structure, typically consisting of walls and other fortifications. Forts are usually built to protect a city, town, or other important location from enemy forces. They can also be used to protect a military base or other strategic location. Forts have been used throughout history to defend against attackers, and they remain an important part of many countries' defense strategies today.