What year was castles first introduced to England?

Castles were introduced to England in the 11th century, specifically after the Norman invasion of 1066 led by William the Conqueror. Initially, these structures served as fortifications and strongholds for the Normans to maintain control over their newly acquired territories and subdue local resistance. Over time, castles evolved in architecture and purpose, becoming not only defensive strongholds but also prestigious symbols of power, political influence, and aristocratic living in England.