The cerebrum is the large, main part of the brain, which serves as the main thought and control center. It is the seat of 'higher level' thought, like emotions and decision making, as opposed to 'lower level' thought, like balance, movements, and reflexes.
The wrinkly, gray outer covering of the cerebrum is called the cerebral cortex, and is made up of layers of neurons with many, many inputs; these cortical neurons function like mini microprocessors or logic gates, and while the cortex is less than 1/4" thick, it is here that all sensation, perception, memory, association, thought, and voluntary physical actions occur.
The inside of the cerebrum beneath the cortex is comprised of white matter, which are myelinated neurons that carry information from one part of the brain to another.
The cerebrum is divided by the longitudinal fissure into a right hemisphere and a left hemisphere. These hemispheres each have their own unique 'persona', if you will. People who are described as being more 'right brained', are more intuitive, whereas people who are more 'left brained' are more logical. Each cerebral hemisphere perceives and controls the opposite side of the body.
The cerebrum is further divided into 5 separate lobes or regions, based upon what cranial bone is over the selected area, except for the Insula, which is cortical tissue buried beneath the junction of the frontal and temporal lobes.