The Castle As Weapon

Here are my notes from the video "Secrets of Lost Empires II:  Medieval Siege".  How do they compare with yours?

What is a SIEGE?  A prolonged, sustained attack on a stationary military position designed to force the defender to surrender either

What features of a castle were designed for defense?

How could attackers defeat a well-defended castle?

Castles were built as "nails holding the landscape down"; they were centralized staging areas for military campaigns

The real success of capturing a castle is credited not to the knights, but to the engineers.