The term Kaiserpfalz (German: [ˈkaɪzɐˌpfalts], "imperial palace") or Königspfalz (German: [ˈkøːnɪçsˌpfalts], "royal palace", from Middle High German phal[en]ze to Old High German phalanza from Middle Latin palatia [plural] to Latin palatium "palace") refers to a number of castles and palaces across the Holy Roman Empire that served as temporary, secondary seats of power for the Holy Roman Emperor in the Early and High Middle Ages. The term was also used more rarely for a bishop who, as a territorial lord (Landesherr), had to provide the king and his entourage with board and lodging, a duty referred to as Gastungspflicht.
Kaiserpfalz is a German word that is a combination of Kaiser, meaning "emperor", which is derived from "caesar"; and Pfalz, meaning "palace", and itself derived from the Latin palatium, meaning the same (see palace). Likewise Königspfalz is a combination of König, "king", and Pfalz, meaning "royal palace".
Like their peers in France, England or Hungary, the medieval emperors of the Holy Roman Empire did not rule from a capital city, but they had to maintain personal contact with his vassals on the ground. This was so-called "itinerant kingship"; a sort of "travelling kingdom" (Reisekönigtum). Because pfalzen were built and used by the king as a ruler within the Holy Roman Empire (rex Romanorum (Römischer König)), the correct historical term is Königspfalz or "royal palace". The term Kaiserpfalz is a 19th-century appellation that overlooks the fact that the king did not bear the title of the Roman Emperor (granted by the Pope) until after his imperial coronation. Unlike a pfalz, where the itinerant ruler enacted his sovereign duties, a royal estate or Königshof is only an economic estate owned by the king, which was only occasionally used by the king on his itinerary.