According to many definitions, disability is a kind of damage, which may be cognition, development, intelligence, spirit, body, feeling or some combination of these. Other definitions describe disability as a social disadvantage caused by such damage. Disability can seriously affect a person's life activities, and may occur from birth or in his or her life.

Disability is a general term that covers impairment, limitation of activity and limitation of participation. Injury is a problem of body function or structure; activity limitation is a difficulty that individuals encounter when they perform tasks or actions; and participation limitation is a problem that individuals encounter when they participate in living conditions. So disability is more than just a health problem. This is a complex phenomenon, reflecting the interaction between a person's physical characteristics and the social characteristics he or she lives in.

Disability is a controversial concept with different meanings in different communities. It can be used to refer to the fixed physical or mental attributes (medical models) that some institutions (especially medical institutions) think are needed. It may refer to the limitation of human being by the limitation of the society of competence (social model). Or the term can be used to refer to the identity of the disabled. Physiological function ability (PFC) is a term related to the level of individual performance. It measures a person's ability to perform daily physical tasks and how easily they are performed. PFC declines with age, leading to weakness, cognitive impairment or physical illness, all of which can lead to the marking of individuals as disabled.

For the purposes of the Americans with Disabilities Act of 1990, the EEOC regulations provide a range of conditions that should easily be attributed to disability: deafness, blindness, intellectual disability (formerly known as mental retardation), partial or complete loss of limbs or mobility disorders requiring wheelchair use, autism, cancer, cerebral palsy, diabetes, epilepsy, HIV/ AIDS, multiple sclerosis, muscular dystrophy, major depression, manic depression, post-traumatic stress disorder, obsessive-compulsive disorder and schizophrenia.

Disabled people are devalued because of the false folk etymology, which the latter says is a reference for begging. It is actually derived from an old game "hand-i '- cap", in which two players trade property and a third neutral person judges the value difference between the property. In the middle of the 18th century, the concept of neutral late odds was extended to the steeplechase. In the steeplechase, according to the referee's estimation of the average running condition of the horse, the weight of the horse is different. In the early 20th century, the term "disabled" was used to describe disabled people (a person with a heavier burden than normal in terms of the extension of disability competitions).

In the obvious differences, the disabled often face stigma. People often respond to the presence of disabled people because of fear, pity, patronage, invasive gaze, disgust or neglect. These responses can, and often do, prevent people with disabilities from accessing social spaces and the benefits and resources they provide. Jenny Morris, a disability writer / researcher, describes how stigma marginalizes people with disabilities:

"It often takes courage to appear in public. How many of us find that we can't dig our strength to do it day by day, week by week, year by year, year by year, and refuse and repel it all our lives? It's not just physical limitations that limit us to our houses and to the people we know. As we all know, every entry into the public world will be dominated by gaze, condescension, compassion and hostility. "

In addition, the face of stigma may bring harm to the psychological emotions of the stigmatized people. One way for the mental and emotional health of the disabled to be adversely affected is by internalizing the oppression they suffer, which may lead them to feel weak, crazy, worthless or many other negative characteristics, which may be related to their condition. The internalization of oppression will damage the self-esteem of the affected people and shape their behaviors in a way that is consistent with the status of accessibility. When people with disabilities are under pressure from people and institutions around them to hide and belittle their disability differences (or "pass"), they often have internal thoughts. According to writer Simi Linton, customs clearance causes the disabled to suffer from community loss, anxiety and self doubt, resulting in deep emotional loss. The media plays an important role in building and strengthening disability related stigma. The description of disability in the media usually defines the existence of the disabled as an indispensable edge in the whole society. These depictions also reflect and influence people's general views on disability differences.

The international access symbol (ISA), also known as the (International) wheelchair symbol, consists of a blue square covered in white and a stylized image of a person sitting in a wheelchair. It is the international standard ISO 7001 image of the International Committee on technology and accessibility (ICTA) of the International Rehabilitation Commission (RI).

Isa was designed in 1968 by Susanne koefoed, a Danish design student. It was first drawn at a radical design conference sponsored by the Scandinavian student organization (SDO). The group organized a summer study course in konstback, Stockholm School of art and design, alternating between workshop courses and large lectures. In these lectures, the keynote was set by Victor Papanek, an American designer and educator. In his works during this period, he also imagined people with physical and mental disabilities as people who need to be re focused. Although there is no evidence that Papanek met koefoed, his influence spread throughout the workshops that drafted the original Isa. Koefoed was responsible for the creation of a symbol to mark accessible accommodations, and an early version of the symbol was shown at an exhibition at the end of the SDO workshop in July 1968. Koefoed's symbol depicts an empty wheelchair. The following year, the icon was widely promoted across Sweden.

Karl mountain, director of Sweden's newly established Institute for the disabled, has also extended koefoed's design to international rehabilitation organizations. RI asked RI's head of the International Committee on technology and accessibility (ICTA) to form a special committee to look for and pass on symbols for its 1969 convention in Dublin. Ask mountain's team to choose from six symbols. When displaying the koefoed logo, several members complained that it was too harsh and illegible. As mountain points out: "the slight inconvenience of this symbol is that the same thick lines may give the impression of lettering. The inconvenience of having a 'head' on the symbol will disappear. " Using the original copy of the design, mountain adds a circle to the top of the seat to give the impression of sitting.

Some disabled activists advocate changing access symbols. Sara hendren and Brian glenney jointly created the accessibility icon project, designed new icons to show active, participating images, and focused on the disabled. Some organizations with disabilities, such as India's enabling unit, are promoting it, while others, such as second thoughts in Connecticut, are refusing to list them as capable. This version of the symbol has been officially used in New York and Connecticut. The revised ISA is in the permanent collection of the Museum of modern art. According to Emma teitel of the Toronto Star, critics say the revised image will still bring social stigma to people with disabilities who do not use wheelchairs.

In May 2015, the Federal Highway Administration rejected new designs for road signs in the United States on the grounds that the fact has not been adopted or recognized by the US access board, the agency responsible for the development of federal accessibility design standards. The design has also been rejected by the international organization for standardization, which has established the normal use of the original symbols in accordance with ISO 7001.