Leukemia is a type of cancer originating in the blood-forming tissues, most commonly the bone marrow. It is characterized by the excessive, uncontrolled production of abnormal white blood cells (leukocytes), which do not function properly and can accumulate in the peripheral blood and marrow, thereby crowding out normal components. The malignancy affects the ability of the circulatory system to transport necessary components, leading to various symptoms dependent on the specific type and degree of bone marrow infiltration. Classification of the disorder is based on the type of cell lineage involved and whether the abnormal cells are acute (rapid progression) or chronic (slow progression). Treatment modalities often involve chemotherapy, targeted agents, or stem cell therapies designed to reduce the abnormal cell burden and restore healthy blood production.