First of all, a little background history: in 1980 the World Health Organization published an initial document titled International Classification of Impairments, Disabilities and Handicaps (ICIDH). In this publication there was an important distinction between impairment (described as a loss or abnormality of physical bodily structure or function, of logic-psychic origin, or physiological or anatomical origin) and two other forms of disability.

These were respectively defined as: any limitation or function loss deriving from impairment that prevents the performance of an activity in the time-lapse considered normal for a human being. 'Handicap' is the disadvantaged condition deriving from impairment or disability limiting a person performing a role considered normal in respect of their age, sex and social and cultural factors. The following list of the main groups of definitions, might help better understand the difference between the terms.

Impairment

1. Impairment of intellectual ability. Other psychological impairment. Impairment of language and wording.
2. Hearing impairment.
3. Visual impairment.
4. Organs impairment.
5. Bone impairment.
6. Scarring and aesthetic impairments.
7. Generalised impairments, sensory and of other kind.

Disability

1. Behavioural Disability
2. Disability of communication
3. Disability in caring of oneself
4. Disability of movement
5. Disability due to body assets, Disability of dexterity
6. Disability of circumstance
7. Disability within specific activities
8. Other restrictions to ability.

Handicap

1. Handicap of orientation.
2. Handicap of physical independence
3. Handicap of mobility
4. Occupational handicaps
5. Handicap in social integration
6. Handicap in economic self-sufficiency
7. Other handicaps

For example, according to the above definitions, a blind person is a person with a visual impairment which gives him a disability of communication, of movement, and involves a handicap of mobility and an occupational disability, just to mention the most important aspects. Therefore just one kind of impairment can cause multiple disabilities and imply several handicaps.

Similarly, a certain kind of handicap can be tied to several disabilities which in turn can derive from one or more impairments. While for the individual, the impairment has a permanent aspect, disability would depend from the activity the individual wishes to uptake. The handicap aspect is the disadvantage he encounters in relations with other individuals, so called 'able' people. A paraplegic person will certainly experience a handicap when wishing to play football, but practically won't experience it while using a personal computer.

THE NEW DOCUMENT OF THE WORLD HEALTH ORGANIZATION (ICF)

The significant aspect of the first WHO document, is that of being able to associate the state of an individual not only to structures and functions of the human body, but to link it to activities and participation to social life of an individual.

The second document entitled International Classification of Functioning, Disability and Health. (ICF). The title already is indicative of a substantial change in the way one confronts him or herself with the problem of presenting a unified language to describe the state of a person.

There are no more referrals to a functional or structural problem, without it being related to a state considered 'healthy'.

As one can see from the transcribed tables below, (this is not the official italian translation of the document). the new document substitutes terms such as impairment, disability and handicap, as terms that indicate something 'missing' preventing a full function of the body. Other terms of the new perspective are:

ICF

Bodily Functions

1. Mental Functions
2. Pain and sensorial functions
3. Function of the voice and speaking
4. Functions of the cardio-vascular, ematologic, immunologic and respiratory systems
5. Functions of the digestive, metabolic and endocrinal systems
6. Genito-urinal and reproductive functions. Neuro-muscular- scheletal functions tied to movement, functions.
7. Functions of the skin and associated structures.

Bodily Structures

1. Structures of the nervous system
2. Eye, Ear and connected structures
3. Structures of voice and speaking
4. Structures of cardio-vascular, immune and respiratory systems
5. Structures of the digestive, metabolic and endocrinal systems
6. Structures of the genito-urinary and reproductive systems
7. Structures connected to movement
8. Skin and associated structures.

Participation and activity

1. Learning of knowledge and its application
2. Homework and requests of general character
3. Communication
4. Mobility
5. Care of one-self
6. Domestic life
7. Interactions and personal relationships
8. Life's main areas
9. Community, civic and social life

Environmental factors

1. Technology and Products
2. Natural environment and man-made chances
3. Support and relationships
4. Attitudes
5. Services, systems and policies

Bodily functions are physiologic functions of bodily systems, including psychological functions. Bodily structures are anatomical parts of the body such as organs, limbs and their components. Activities is the execution of an action on behalf of an individual. Participation is the involvement of the individual in a life situation. Environmental factors are characteristics of the physical and social world and the attitudes that can have an impact in the individual's life. Classification as above shown, stops at the first two levels, however in the WHO's document there are more detailed levels extending classifications into further sub-classifications. At every level of classification a code is assigned.

So, for example, the classification b11420 in inserted in the following level gerarchy:

b Bodily structures
b1 Mental functions
b11 Global mental functions
b114 Orientation functions
b1142 Orientation towards others
b11420 Orientation towards one-self.

To this classification is associated the definition of mental functions producing awareness of one's identity. The ICF document, covers all aspects of human health, grouping them under the main 'health domain' inclusive of sight, hearing, walking, learning and remembering as well as those domains connected to the health domain, like mobility, learning, social life and so on. It is very important to clarify the following: ICF does not relate only to people with disabilities but to everyone, therefore it has universal use and value. In relation to the hundred of 'voices' of classification to each individual can be associated one or more qualifying 'voices' quantifying his functionality. As for bodily functions and structures, the qualifying voice can assume the following values:

Similar classification exists for activities for which there are restrictions and for participation for which limitations can exist. Finally, in relation to environmental factors, there are barriers. The 'positive' classification starting from functionality, has the advantage of not having to specify the causes of an impairment or disability, but it only indicates its effects. It should be noted that since the word 'handicap' has been abandoned, the meaning of the word disability has been expanded to cover the restriction of activity as well as limitation to participation.