Impairment is a loss or abnormality of psychological, physiological, or anatomical structure or function.

Impairments and disabilities may be temporary or permanent, reversible or irreversible, and progressive or regressive. The situation people find themselves in may determine to what degree a disability is handicapping for them. It is evident from the definitions above that a handicap is the result both of an impairment and of environmental conditions  If environmental barriers are taken away, the person will still be impaired, but not necessarily handicapped. It should also be noted that the definition of disability as distinct from handicap is not without problems, in particular the formulation "considered normal for a human being", and many people with disabilities do not distinguish their use.

The functional ability of people who are diagnosed as having the same impairment or disability may vary widely. For example, some people who are legally blind may be able to utilize differences in light intensity, while others are unable to perceive such differences. People who have clinically similar hearing impairments, as shown on audiograms, may use quite different aspects of the acoustic information available to them. The degree of handicap may vary significantly and may be specific to certain situations.

The cooperation of teachers and parents of students with disabilities implies various complex contextual, cognitive and personal variables and affects somewhat the quality and course of the child's education. A systemic approach to the issue of the development of cooperation between the school and the family of a SWD presumes knowledge and understanding of the structure and functioning of the