A castle is a type of
fortified
A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''face ...
structure built during the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
predominantly by the
nobility
Nobility is a social class found in many societies that have an aristocracy (class), aristocracy. It is normally ranked immediately below Royal family, royalty. Nobility has often been an Estates of the realm, estate of the realm with many e ...
or royalty and by
military orders. Scholars debate the scope of the word ''castle'', but usually consider it to be the private
fortified residence of a lord or noble. This is distinct from a
palace
A palace is a grand residence, especially a royal residence, or the home of a head of state or some other high-ranking dignitary, such as a bishop or archbishop. The word is derived from the Latin name palātium, for Palatine Hill in Rome which ...
, which is not fortified;
from a fortress, which was not always a residence for royalty or nobility; from a ''pleasance'' which was a walled-in residence for nobility, but not adequately fortified;
and from a fortified settlement, which was a public defence – though there are many similarities among these types of construction. Use of the term has varied over time and has also been applied to structures such as
hill fort
A hillfort is a type of earthwork used as a fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage. They are typically European and of the Bronze Age or Iron Age. Some were used in the post- ...
s and 19th-20th century homes built to resemble castles. Over the approximately 900 years when genuine castles were built, they took on a great many forms with many different features, although some, such as
curtain walls,
arrowslit
An arrowslit (often also referred to as an arrow loop, loophole or loop hole, and sometimes a balistraria) is a narrow vertical aperture in a fortification through which an archer can launch arrows or a crossbowman can launch bolts.
The interi ...
s, and