Castles had some common features, but there was no such thing as a typical castle. They were built over different times by different people with different materials.
Warwick castle was first built as a wooden motte-and-bailey castle (a castle built on a mound with a moat/dictch around it)It was rebuilt a century after as a stone castle.
The first real castles were built in England by the invading Normans to remind the English that the Normans were now in control. Castles were built to provide safety and protection. They were also...