The International Classification of Diseases (or, to give it its full title – The International Classification of Diseases and Related Health Problems) is the most popular worldwide text on disease diagnosis.
The ICD has a history from 1860 when Florence Nightingale stated that there was a great need for a classification system for hospitals. From then several texts were developed and joined by different contributions until in 1949 a two-volume book was published. This was technically the 6th version of the ICD text but was the first under the instruction of the World Health Organisation (WHO) who took charge of the text the previous year.
The ICD defines, states symptoms and categorises the entire spectrum of diseases. This includes mental illness and so there is some controversy and debate between the DSM and the ICD. Whilst they look on the whole relativity similar in their diagnosis there are some distinctions, especially surrounding personality disorders, which remain controversial.