This chapter describes general categories of exceptionality in which special education may be needed. Students may need special education for a variety of reasons. Chief among these reasons are special difficulties in thinking; learning an academic subject or subjects; focusing and sustaining attention or being reasonably still and accessible to teaching; recognizing and controlling emotions or behavior; communicating through speech and language; hearing; seeing; moving or maintaining physical well-being; severe and multiple disabilities. The nature and extent of individual differences are the foundation for defining special education. Individuals with both a disability and a special talent or gift are considered twice exceptional. The common terms used for the categorical designation of the exceptionalities are intellectual disability, emotional disturbance, behavioral and communication disorders, hearing impairment and deafness, vision impairment and blindness, physical disabilities, autistic spectrum disorders, traumatic brain injury, multiple and severe disabilities, and gifted and talented.