A castle contains several main parts to it some serving as defense. One main defense system is the moat. The moat is a ditch outside of the castle which prevents enemies from getting close to the building. The next defense would be the castle's turrets. They are rounded and have crenels at the top which allow archers to shoot down at intruders. Also, the rounded shape will take less impact and deflect arrows shot from below. The drawbridge, which is the only way across the moat in to the castle, is also a defense. It keeps enemies out and the people in the castle safe. Another defense would be the high and strong curtain walls. They intimidate people from trying to climb into the outer bailey of the castle. Once across the drawbridge, yet again there is another defense. They are the murder holes. They can shoot arrows or pour hot sand onto intruders. If they do survive the murder hole attacks, then they will have to break open the portcullis to get into the castle structure itself. The portcullis is a heavy gate made of oak and iron which again, keeps intruders out.
Beyond the portcullis is the outer bailey which is the courtyard surrounding the inner bailey. This courtyard has the well(s), stables, and shops. The outer bailey may also have a church. Even farther than the outer bailey, the inner bailey can be found. There is a curtain wall around this courtyard too. The inner bailey is similar to the outer bailey, but the only difference is that it surrounds the keep. This is where the lord and lady live. There is another yet smaller courtyard in the keep. There are also halls where great feasts are held.
There has to be great weapons to defend a castle. Some used were crossbows, longbows, and magonels. These were used to defend the castle when taken under siege. The crossbow was amazingly accurate and could shoot arrows far. The same went for the long bow; only it needed more manpower to make it shoot far. The magonels were used to throw boulders down at intruders. Some used against the castle would be the battering rams, ballistas, and catapults. The battering rams were used to hit the walls. Hopefully, they could hit down the wall. The ballistas could shoot arrows at the drawbridge and portcullis. The catapults were used to throw stones at walls.