Assistive technology (AT) can be defined as any item, piece of equipment, or product system, whether acquired commercially off the shelf, modified, or customized, that is used to increase, maintain, or improve the functional capabilities of individuals with disabilities.
- National Institute of Standards and Technology

It can be low tech (such as an object, a marker, a slate and stylus) or high tech, such as electronic devices, computer software, or switch-activated materials.