What is the main part of a castle called?

Generally, when speaking about the living quarters there were 2 areas that would come to mind; The barracks and the very inner keep. When speaking about a Castle, the Barracks were where the soldiers and guards slept, rarely would a citizen be found within the military infrastructure. However, inside the main keep of the castle, there were generally upper rooms ordained the Inn or noble suites. Aside from any other housing the Inn or Noble suites was the most common place for the nobility to sleep.