A clinical coder—also known as clinical coding officer, diagnostic coder, medical coder, or nosologist—is a health information professional whose main duties are to analyse clinical statements and assign standard codes using a classification system. The Health data produced are an integral part of health information management, and are used by local and national governments, private healthcare organizations and international agencies for various purposes, including medical and health services research, epidemiological studies, health resource allocation, case mix management, public health programming, medical billing, and public education. For example, a clinical coder may use a set of published codes on medical diagnoses and procedures, such as the International Classification of Diseases (ICD), the Healthcare Common procedural Coding System (HCPCS), and Current Procedural Terminology (CPT) for reporting to the health insurance provider of the recipient of the care. The use of standard codes allows insurance providers to map equivalencies across different service providers who may use different terminologies or abbreviations in their written claims forms, and be used to justify reimbursement of fees and expenses. The codes may cover topics related to diagnoses, procedures, pharmaceuticals or topography. The medical notes may also be divided into specialities for example cardiology, gastroenterology, nephrology, neurology , pulmonology or orthopedic care. There are also specialist manuals for oncology known as ICD-O (International Classification of Diseases for Oncology) known as "O Codes" which are also used by tumor registrars (who work with cancer registries) as well as dental codes for dentistry procedures known as "D codes" for further specifications. A clinical coder therefore requires a good knowledge of medical terminology, anatomy and physiology, a basic knowledge of clinical procedures and diseases and injuries and other conditions, medical illustrations, clinical documentation (such as medical or surgical reports and patient charts), legal and ethical aspects of health information, health data standards, classification conventions, and computer- or paper-based data management, usually as obtained through formal education and/or on-the-job training. In practice The basic task of a clinical coder is to classify medical and health care concepts using a standardised classification. Inpatient, mortality events, outpatient episodes, general practitioner visits and population health studies can all be coded. Clinical coding has three key phases: a) Abstraction; b) Assignment; and c) Review. Abstraction The abstraction phase involves reading the entire record of the health encounter and analysing the information to determine what condition(s) the patient had, what caused it and how it was treated.