Neural development refers to the processes that generate, shape, and reshape the nervous system, from the earliest stages of embryogenesis to the final years of life. The study of neural development aims to describe the cellular basis of brain development and to address the underlying mechanisms. The field draws on both neuroscience and developmental biology to provide insight into the cellular and molecular mechanisms by which complex nervous systems develop. Defects in neural development can lead to cognitive and motor impairment, as well as neurological disorders such as Rett syndrome, and intellectual disability.