The human brain is the most complex organ in a human's body. A nerve center controlling any thought processes, coordinating muscular actions as well as processing sensory information, makes it work. It connects it with the rest of its areas, trillions of synapses, and the rest with about 86 billion neurons through complex networks. This review entails some simple physiological brain features that include functional domains, neurochemical signaling, and structural structure. The three major macro-regions utilized for unique functions include the cerebral cortex, cerebellum, and brain stem. Higher-order cognitive functions like language, logic, memory, and visual processing are performed by the frontal, parietal, temporal, and occipital lobes of the cerebral cortex. The brain stem controls autonomic activities, breathing, and heart beating. The cerebellum coordinates for performance in motor and balance functions. Neurotransmitters are released at synapses to allow the transmission of impulses between neurons, and neurotransmission is a vital physiological process. Above all, very important neurotransmitters control operations at the neurons' side. These are simple reflexes and complex actions using glutamate as the excitatory neurotransmitter and gamma-amino butyric acid, or GABA, as the inhibitory neurotransmitter. These neurotransmitters are mainly involved with regulatory functions such as regulation of reward mechanisms and mood, besides neuropeptides and neuro- modulators, like serotonin and dopamine. It depends upon neu- r o plasticity, wherein the brain can reconfigure itself because of new connections between the neurons. Injury, environment, experience, and more modulate the plastic and versatile ability of this particular system. BBB is a protective interface regulating the chemical flux from circulation into the brain to maintain homeostasis. The brain learns and responds to stimuli after some physiological interactions. Therefore, cognitive functions continue through life. Knowing about brain physiology is known to be useful for a comprehension of solutions to neurological problems and therapeutic approaches. The fact being so, research effort, therefore, will continue into the mysteries of activities of the brain to unveil the basic mechanisms underlying alertness, emotion, and consciousness.