Intellectual disability (ID) in children is a condition characterized by significant limitations in intellectual functioning and adaptive behavior. Intellectual functioning refers to a child's ability to learn, reason, solve problems, and think abstractly, while adaptive behavior refers to a child's ability to adapt to everyday life and interact with others in a socially appropriate manner. 

Children with ID may have difficulties with communication, self-care, social skills, and academic performance. The severity of these difficulties can vary widely, ranging from mild to severe. In some cases, ID may be caused by genetic or chromosomal abnormalities, while in other cases, it may be caused by environmental factors such as malnutrition, exposure to toxins, or brain injury.