Beyin is the Turkish word for "brain," which is the central organ of the nervous system in humans and many animals. It is responsible for processing sensory information, controlling movements, and regulating bodily functions. The brain is made up of billions of neurons that communicate with each other through electrical and chemical signals. The structure of the brain includes several key parts, such as the cerebrum, cerebellum, and brainstem. Each part has specific functions, like decision-making, coordination, and regulating vital processes like breathing and heart rate. Understanding the brain is crucial for fields like neuroscience and psychology.