Equipment or software items designed or used to compensate for areas of disability or functional limitations.  It allows persons with disabilities the same access to information and production as their peers.

According to Technology-Related Assistance for Individuals with Disabilities ACT of 1988 (Tech Act; P.L. 100, 407), and AT device refers to "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."  Rasking and Bryant (1996) note that in some instances the device may assist, augment, or supplement task performance in a given area of disability; while in others, it may be used to circumvent or bypass specific deficits entirely.