The brain's largest part is the cerebrum. Occupying about 85% of the brain's total weight, it is divided into two hemispheres and further subdivided into four lobes: frontal, parietal, temporal, and occipital. The cerebrum is responsible for a wide range of functions, including sensory processing, reasoning, voluntary movement, language, and decision-making. It also plays a crucial role in higher cognitive functions such as memory and learning. The complexity and importance of the cerebrum make it a central focus in neuroscience and psychology as we seek to understand the human brain.