Intellectual disability or ID is a term used when there are limits to a person’s ability to learn at an expected level and function in daily life. Levels of intellectual disability vary greatly in children. An intellectual disability could cause a child to learn and develop more slowly than other children of the same age. It could take longer for a child with an intellectual disability to learn to speak, walk, dress or eat without help, and they could have trouble learning in school. Intellectual disability can happen any time before a child turns 18 years old, even before birth.