Motte and Bailey Castles were a common design of castles in the Middle Ages, combining ease of construction with defensibility. Motte and Bailiey castles were the earliest form of castles built completely from scratch by the Normans.
The model above shows how they would have looked.
As their name suggests, they had two parts, the Motte and the Bailey.
The Motte was a large hill made of earth on which was built a wooden keep or lookout. The outer edge was then surrounded with a large wooden fence called a palisade.
The Bailey was separated from the Motte by a wooden bridge that could be removed if the Bailey was occupied by enemies. The Bailey was the part of the castle where people lived and animals were kept. A large castle might have more than one Bailey.
To give added protection to the castle, both the Motte and Bailey would be surrounded by a ditch, sometimes filled with water. A drawbridge was used for access to the castle.