Wheelchairs are assistive devices for people with mobility disabilities. Mobility equipment may be divided into two general categories, manual or powered, with wheelchairs falling under both.
Manual or user-propelled wheelchairs consist of a chair attached to two large wheels in the back, and two caster wheels in the front. People use the push rims attached to each large wheel to move.
The cost for a manual wheelchair varies depending on materials and design. Lower-cost models are heavier and more difficult to maneuver. Higher-cost designs tend to utilize light-weight rigid tubular metal frames and have easily removable wheels. 
Powered wheelchairs are typically used by people who cannot push a manual chair. These chairs include motors, batteries, and either standard or customized control devices. Some advanced self-propelled wheelchairs contain collision avoidance controls and sophisticated systems to determine control intentions from small movements. All of these features add to the weight of the wheelchair.
There are also specialized wheelchairs for sports and improved performance in daily activities. Some climb stairs, and wheelchairs that elevate a person to the standing position also exist. However, the number of people using these types of wheelchairs is limited.
People who need and use wheelchairs are protected by the Americans with Disabilities Act. This Act prohibits discrimination against individuals with disabilities in all public and private places that are open to the general public.
