A wheelchair is a mobility device designed to assist individuals who have difficulty walking or are unable to walk due to illness, injury, or disability. It typically consists of a seat, footrests, and four wheels, with two larger rear wheels and two smaller front wheels. Wheelchairs can be manually operated by the user or an attendant, or they can be powered by electric motors for easier movement. They are essential for providing independence and improving the quality of life for many people with mobility challenges.