Williams castles were mostly made out of wood because that was the most common material in their time. Sometimes the castles were made out of stone because it’s stronger then wood but it was more expensive.
Most of the time they would build the castles high up on mountains so they get the advantage, because they stay up there and the enemy needs to come up and when they get to the top they will be too tired to fight.
People sometime attacked castle by digging a tunnel and landing in the castle so if the people in the castle knew they will dig to get in the castle they will dig to, and kill them.
Also the attackers used ladders to get over the wall and the people in the castle push it away from the wall so the attackers fell, so the made an advance to the ladder so it didn't fall, so the defenders put mud everywhere outside the castle because the ladder was moved by wheels so by putting mud on the floor it will be hard to take the ladder with you, and even if they got there they will pour hot oil over them.
Castles needed to change because if every castle was made out of wood it will be burnt down by invaders or it will rot down, and that's why it needed to change to stone because stone doesn't rot or get burnt.
But the bad things about stone its more expensive then wood but stone is stronger and the other bad thing about stone is that's there is less of it.
Castle changed because they needed to get stronger materials then wood because with that will rot and its not that strong so they made castles out of stone which was stronger and they made the castles bigger and with round towers to make it stronger.
Also they changed where they put it like now they put it on top of hills.
I have chosen the Windsor castle it has three main towers ones called Edward III tower the other is called curfew tower the other one has not been named, it has 2 apartments a private one and an state, it has 2 gate way 1 for the principal and one for the peasant, it also has an St. George’s chapel, and 2 terraces, 1 on the north and 1 on the east , it has a lower and upper ward and it has a south wing and a long walk path way.