ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases.
The code set allows more than 14,400 different codes and permits the tracking of many new diagnoses. The codes can be expanded to over 16,000 codes by using optional sub-classifications. The detail reported by ICD can be further increased, with a simplified multi-axial approach, by using codes meant to be reported in a separate data field.
The WHO provides detailed information about ICD online, and makes available a set of materials online, such as an ICD-10 online browser, ICD-10 Training, ICD-10 online training, ICD-10 online training support, and study guide materials for download.
The International version of ICD should not be confused with national Clinical Modifications (CM) of ICD that frequently include much more detail, and sometimes have separate sections for procedures. The US ICD-10 Clinical Modification (ICD-10-CM), for instance, has some 68,000 codes. The US also has the ICD-10 Procedure Coding System (ICD-10 PCS), a coding system that contains 76,000 codes not used by other countries.
Be aware that many ICD-10 references in Wikipedia refer to ICD-10 CM (US modification), in particular if they have 5 digits (xxx.xx).
Work on ICD-10 began in 1983 and was completed in 1992.
Some 25 countries use ICD-10 for reimbursement and resource allocation in their health system. A few of them made modifications to ICD to better accommodate this use of ICD-10. The article below makes reference to some of these modifications. The unchanged international version of ICD-10 is used in about 110 countries for cause of death reporting and statistics.
ICD-10-AM (Australian Modification)
1 July 1998 Victoria, New South Wales, Australian Capital Territory and Northern Territory implemented ICD-10-AM.1 July 1999 Queensland, South Australia, Tasmania and Western Australia implemented ICD-10-AM.
The Czech Republic adopted ICD-10 in 1994, one year after official release from WHO. The Czech republic uses the international version without any local modifications. The Czech Republic adopted all updates to the international version (namely in 2004,2010,2011,2012).
A Korean modification has existed since 2008.
1 January 2005 Pretoria, Johannesburg, Cape town
The current Swedish translation of ICD-10 was created in 1997. A clinical modification has added more detail and omits codes of the international version in the context of clinical use of ICD:
The codes F64.1 (Dual-role transvestism), F64.2 (Gender identity disorder of childhood), F65.0 (Fetishism), F65.1 (Fetishistic transvestism), F65.5 (Sadomasochism), F65.6 (Multiple disorders of sexual preference) are not used in Sweden since 1 January 2009 according to a decision by the present Director General of The National Board of Health and Welfare, Sweden. The code O60.0 (Preterm labor without delivery) is not used in Sweden; instead, since 1 January 2009, the Swedish extension codes to O47 (False labor) are recommended for use.
A Thai modification has existed since 2007; the Ministry of Public Health has ICD 10 TM. and 1 of 3 first used ICD-10 Code with Czechoslovakia and Denmark in 1994
The deadline for the United States to begin using Clinical Modification ICD-10-CM for diagnosis coding and Procedure Coding System ICD-10-PCS for inpatient hospital procedure coding is set at October 1, 2015, another year delayed from the previous 2014 deadline The deadline prior was October 1, 2013. All HIPAA "covered entities" must make the change; a pre-requisite to ICD-10 is the adoption of EDI Version 5010 by January 1, 2012. Enforcement of 5010 transition by the Centers for Medicare & Medicaid Services (CMS), however, was postponed by CMS until March 31, 2012, with the federal agency citing numerous factors, including slow software upgrades. The implementation of ICD-10 has been subject to previous delays. In January 2009, the date was pushed back by two years, to October 1, 2013 rather than a prior proposal of October 1, 2011. The most recent pushback of the implementation date has inspired a mixed reaction from the healthcare community.
Even though the deadline for ICD-10 has been pushed back repeatedly, CMS recommends that medical practices take several years to prepare for implementation of the new code set. The basic structure of the ICD-10 code is the following: Characters 1-3 (the category of disease); 4 (etiology of disease); 5 (body part affected), 6 (severity of illness) and 7 (placeholder for extension of the code to increase specificity) . Not only must new software be installed and tested, but medical practices must provide training for physicians, staff members, and administrators. They will also need to develop new practice policies and guidelines, and update paperwork and forms. For convenience, practices may also create "crosswalks" that will convert their most frequently used ICD-9 codes to the ICD-10 equivalents. 
Dubai Health Authority (DHA) introduced ICD-10 in 2012.
Language versions should not be confused with clinical versions. ICD has been translated into 42 languages.