Neurodevelopmental disorder is a disorder of typical brain function (abnormalities), which develops in the course of an individual's development. These brain abnormalities are subsequently translated into a variety of physiological, behavioural and cognitive deficits, one of which is an anomalous pattern of social interaction skills. Difficulty communicating with others is a common feature of the phenotype of developmental disorders, which include autism spectrum disorder, attention deficit hyperactivity disorder, psychopathic disorder, .... etc. These disorders are characterized by distortions and difficulties in the social sphere. They usually appear early and have a neurodevelopmental origin. This book details the findings of a study conducted to find out what developmental delay is, how it affects the appearance of these disorders, and how it turns from a developmental delay that can disappear over time, to a global developmental disorder that causes intellectual disabilities, and language disorders. In addition, to identify the differences between these disorders and their symptoms, especially when they overlap together, causing confusion in accurately diagnosing the condition, and thus affecting the development of a correct treatment plan suitable for it.