What are the main features of a Norman castle?

Roughly, Gothic architecture, mainly in churches and cathedrals, has arches that come to a bit of a point at the top, steeply-pitched stone roofs (previous architecture had flatter wood roofs that would burn and collapse into the church), and had interior outer aisles with clerestory Windows up high, and also vaulted ceilings whose crossings feature groined 'joints'.