In English a palace is the home of a head of state or other high-ranking public figure. In some countries, such as Italy, the term is also applied to some private mansions. Many palaces are now put to other uses such as parliaments or museums. The word is also sometimes used to describe a lavish public building which does not house a public figure; this use is intended to convey that the building is a "people's palace", where a sort of civic consciousness resides.
Historians apply the term "palace" anachronistically, to label the complex structures of Minoan Knossos, or the Mycenaean palace societies, or the 4th century incompletely-Hellenized palace system of Philip of Macedon's Vergina— or palaces outside the European world entirely.
A castle (from the Latin castellum) is a structure that is fortified for defence against an enemy and generally serves as a military headquarters dominating the surrounding countryside. The term is most often applied to a small self-contained fortress, usually of the Middle Ages. The term castle, however, has a history of scholarly debate surrounding its exact meaning. It is usually regarded as being distinct from the general term fortress in that it describes a building which serves as a residence and commands a specific territory.
Despite this, "castle" sometimes denotes a citadel (such as the castles of Badajoz and Burgos) or small detached forts d'arrêt in modern times and, traditionally, in Britain it has also been used to refer to prehistoric earthworks (e.g. Maiden Castle).