Definition: International Classification of Diseases and Related Health Problems
A classification of diseases may be defined as a system of categories to which morbid entities are assigned according to established criteria. There are many possible axes of classification and the one selected will depend upon the use to be made of the statistics to be compiled. A statistical classification of diseases must encompass the entire range of morbid conditions within a manageable number of categories.
The Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems is the latest in a series that was formalized in 1893 as the Bertillon Classification or International List of Causes of Death.
Version 10, apart from slight changes in its denominations, presents two important innovations: 1) in addition to the earlier functions, it also has a central classification with links to other medical classifications which are either more detailed or complement another health aspect. For the first time, it introduces the concept of a "family" of classifications of diseases and human health problems within which ICD-10 is the basic core and on the basis of its three-digit Detailed List connections are established with the other classification; and 2) the coding system has become alphanumeric
World Health Organisation