Reactive attachment isorder (RAD) is the diagnostic term for severe and relatively uncommon disorders of attachment that can affect children. RAD is characterized by markedly disturbed and developmentally inappropriate ways of relating socially in most contexts. It can take the form of a persistent failure to initiate or respond to most social interactions in a developmentally appropriate way—known as the "inhibited" form—or can present itself as indiscriminate sociability, such as excessive familiarity with relative strangers—known as the "disinhibited form". The term is used in both the World Health Organization's International Statistical Classification of Diseases and Related Health Problems (ICD-10) and in the DSM-IV-TR, the revised fourth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). In ICD-10, the inhibited form is called RAD, and the disinhibited form is called "disinhibited attachment disorder", or "DAD". In DSM, both forms are called RAD; for ease of reference, this article will follow that convention and refer to both forms as reactive attachment disorder.