Haematology is the branch of medicine that is concerned with the study of blood, the blood-forming organs, and blood diseases. Haematology includes the study of etiology, diagnosis, treatment, prognosis, and prevention of blood diseases. Haematology includes the care and treatment of patients with haematological diseases, although some may also work at the haematology laboratory viewing blood films and bone marrow slides under the microscope, interpreting various haematological test results. Haematology is a distinct subspecialty of internal medicine, separate from but overlapping with the subspecialty of medical oncology.