A mobility aid is a device designed to assist walking or otherwise improve the mobility of people with a mobility impairment. There are various walking aids which can help people with impaired ability to walk, and wheelchairs or mobility scooters for more severe disability or longer journeys which would otherwise be undertaken on foot. For people who are blind or visually impaired the white cane and guide dog have a long history of use. Other aids can help with mobility or transfer within a building or where there are changes of level. Traditionally the phrase "mobility aid" has applied mainly to low technology mechanical devices. The term also appears in government documents, for example dealing with tax concessions of various kinds. It refers to those devices whose use enables a freedom of movement similar to that of unassisted walking or standing up from a chair. Technical advances can be expected to increase the scope of these devices considerably, for example by use of sensors and audio or tactile feedback. Walking aids Walking aids include assistive canes (commonly referred to as walking sticks), crutches, and walkers. As appropriate to the needs of the individual user, these devices help to maintain upright ambulation by providing any or all of: improved stability, reduced lower-limb loading and generating movement. Improved stability By providing additional points of contact the walking aid provides both additional support and a wider range of stable centre of gravity positioning. Reduced lower-limb loading By directing load through the arms and the walking aid, lower impact and static forces are transmitted through the affected limbs. Generating Movement The walking aid and arms can substitute for the muscles and joints of the spine, pelvis and/or legs in the generation of dynamic forces during walking. Cane The cane or walking stick is the simplest form of walking aid. It is held in the hand and transmits loads to the floor through a shaft. The load which can be applied through a cane is transmitted through the user's hands and wrists and limited by these. Crutches A crutch also transmits loads to the ground through a shaft, but has two points of contact with the arm, at the hand and either below the elbow or below the armpit. This allows significantly greater loads to be exerted through a crutch in comparison with a cane. Canes, crutches, and forearm crutch combinations Devices on the market