“Intellectual and developmental disabilities (IDD) are disorders that are usually present at birth and that negatively affect the trajectory of the individual’s physical, intellectual, and/or emotional development. Many of these conditions affect multiple body parts or systems.
Intellectual disability1 starts any time before a child turns 18 and is characterized by problems with both:
- Intellectual functioning or intelligence, which include the ability to learn, reason, problem solve, and other skills; and
- Adaptive behavior, which includes everyday social and life skills.
The term “developmental disabilities” is a broader category of often lifelong disability that can be intellectual, physical, or both.2
“IDD” is the term often used to describe situations in which intellectual disability and other disabilities are present.3″ (NIH)