The development of the brain is a highly complex process that includes embryological, genetic, biochemical, physiological, and environmental events. The brain biology and its developmental procedures function within an extremely controlled, inherently planned, and constantly changing context. The process of brain development is lifelong, starting at the beginning of the third gestational week. Some processes are completed at birth, whereas others continue to develop throughout life. Brain development includes neurulation, proliferation, migration, differentiation, synaptogenesis, and myelination. The events contributing to brain development are based on molecular mechanisms of genetic expressions to environmental input. The disruption of either can alter the anatomical, physiological, and biological outcomes. During the gestational period and/or later, environmental pollution results in detrimental effects that can impair the developmental, functional, and cognitive process of brain biology.