Castles used to be a type of housing, usually medieval forts. They were the property of lords who exerted a sort of influence on their lands.

The very first castles were wooden-built. Wood was quickly changed for heavy stones, to make castles more robust and a reflection of the Lords power and authority. Drawbridges were added on the structures and moats were dug on the surroundings of the castles in order to safeguard and protect at best the castle's premises from hypothetic attacks.

Castles were key places in the strategy of defense and control of a land. The volume of a castle had to be quite bulky to overcome a siege warfare technique. Yet, they were arranged in a luxury and comfy manners for the noblemen and monarchs to live a fast lane. Castles were not only offensive structures, but a place providing entertainments for the Knights and their heirs.

In the Middle Ages, castles were erected almost everywhere in Europe, and their structure evolved during the crusades.
In a war over land control and domination, castles were both offensive and defensive edifices. The other typical features of these edifices are surrounding walls and rounded towers.
Walls were so hard to break, that the castles inhabitants were able to gain time before attackers manage to break through the place.

In Europe, and mainly in France, castles refer to the medieval fortresses but the same word (Chateau) is used to speak about the residence of the gentry after the feudal age.