In spite of a refined classification on the functioning or disability accredited by World Health Organization (WHO, 2001), explicit concepts or definitions of health, disablement and its related terminologies of impairment, disability, handicap, activity limitation and participation restriction are generating considerable confusion in Korea. It is very important to understand the new concepts of these different changing terms in all health related fields. International Statistical Classification of Diseases and Related Health Problems (ICD-10) has reported diagnosis or mortality statistics, but the report did not cover the health status of living populations or information about non-fatal health outcomes. In order to rectify this situation, WHO developed a new tool for the classification of the consequences of disease, namely the International Classification of Impairments, Disabilities and Handicaps (ICIDH) in 1980. Following several revisions, WHO announced the International Classification of Functioning, Disability and Health (ICF) in 2001, which was not based on a medical or a social model, rather on bio-psycho-social and interactive model. WHO recommend the use of the two different classifications to provide relevant and updated information on diagnosis of disease (s) with ICD-10 and also on assessment of functioning or disability with ICF.