Assistive technology (AT) refers to "assistive products and related systems and services developed for people to maintain or improve functioning and thereby promote well-being Assistive technologies include any product, piece of equipment or item used to maintain, improve or increase the functional ability of people with disabilities. Assistive products can be made, modified or bought. Assistive devices range from simple, low-technology devices (e.g. canes), to complex, high-technology devices (e.g. motorized wheelchairs). The World Health Organization created the Priority Assistive Products List (APL) to improve access to assistive products.