The keep, which may be referred to as the primary tower, was the castle's social center at the heart of the castle. If attackers made it into the castle, the first priority was to protect the lord -- defend the keep, to the death if necessary.
The keep consisted of the lord's family suite, often a chapel, and a great hall (dining hall). The great hall was the place where large, elaborate feasts were held. Facing the other tables, the lord and his family often sat at a table where the floor was terraced up one step. Off of the great hall was a kitchen, a pantry, and a buttery, where from wine and ale were issued. Directly off the hall, was the screens. This was a narrow strip cut off from the hall body by a carved wooden screen. Meat was cut and seasoned in this room just before the meal was served. Often, below the hall was a basement room for storage.
Starting at the next level up was the lord's private suite where he and his family lived. The actual bedrooms were up a floor. The lord's suite usually had access to the chapel.