ICD is the foundation for the identification of health trends and statistics globally, and the international standard for reporting diseases and health conditions. It is the diagnostic classification standard for all clinical and research purposes. ICD defines the universe of diseases, disorders, injuries and other related health conditions, listed in a comprehensive, hierarchical fashion that allows for:
- easy storage, retrieval and analysis of health information for evidenced-based decision-making;
- sharing and comparing health information between hospitals, regions, settings and countries; and
- data comparisons in the same location across different time periods.
Uses include monitoring of the incidence and prevalence of diseases, observing reimbursements and resource allocation trends, and keeping track of safety and quality guidelines. They also include the counting of deaths as well as diseases, injuries, symptoms, reasons for encounter, factors that influence health status, and external causes of disease.
Biological classification is also known as taxonomy . It is a science, and like most sciences has evolved over time. At various times different principles were adopted, and it is not rare for different scientists to use different methods. Since the early 20th century, groupings are supposed to fit the Darwinian principle of common descent . These days, molecular evolution studies, which use DNA sequence analysis as data, are popular. This is often called "phylogenetics", a branch or form of cladism . This approach creates an evolutionary Tree of life (biology) and uses characters ( traits ) to decide on the branches of the taxonomy .