They were not called "keeps" until after the medieval period had ended (and castles were no longer being built). The word used at the time was donjon.
The word donjon gives a clue as to the main function of the building - it comes from Latin dominium, a place of lordship. The main purpose was to establish authority and domination over an area with a huge, strong tower which could be plainly seen for miles. It also served as a centre of administration for records, for collecting taxes, for judicial trials and for granting legal permissions.
In the very rare times of war the donjon served as a final refuge for the castle garrison - but it also became a prison for them since there would be no way out and they could eventually starve. Donjons looked impressive, but as defensive structures they had limited value - the garrison could only defend from the roof or from arrow slits at certain points, but there were always blind spots they could not cover.
to keep the fire going
to show how rich and powerful the king was in that realm.
The third period of the Middle Ages was the Late Middle Ages. The first is called the Early Middle Ages or the Dark Age. The second period was the High Middle Ages.
middle ages
There was no nylon in the Middle Ages. Nylon was invented in the 20th century; the Middle Ages ended in the 15th.
Castles in the Middle Ages were used to keep out enemies.
the middle ages didnt have a purpose. they were a time period. im not really sure when, but it was the time of knights and lords and ladies and stuff llike that.
cows.
to keep the fire going
To bring them luck.
to show how rich and powerful the king was in that realm.
The period of time from 500 AD to 1500 AD is called the Middle Ages.
Castles were built as a form of protection and were strongholds against the enemy.
Simply to attract customers. Market traders do it to this day.
to keep th eking/queen safe
Barns where used for the animals and to keep the food there.
A tower might also have been called a keep.