Leukemia is a type of cancer that affects the blood-forming tissues of the body, including the bone marrow and the lymphatic system. It is characterized by the rapid growth of abnormal blood cells that do not function properly. There are many types of leukemia, which are divided based mainly on whether the leukemia is acute (fast-growing) or chronic (slower-growing), and whether it starts in myeloid cells or lymphoid cells. The major types of leukemia are:

• Acute lymphocytic leukemia (ALL): This is the most common type of leukemia in young children, but it can also occur in adults.
• Acute myelogenous leukemia (AML): This is the second most common form of childhood leukemia and one of the most common forms for adults.
• Chronic lymphocytic leukemia (CLL): This is the other most common form of adult leukemia.
• Chronic myelogenous leukemia (CML): This type of leukemia is associated with an abnormal chromosome called the Philadelphia chromosome.

Leukemia usually involves the white blood cells, which are potent infection fighters that normally grow and divide in an orderly way, as the body needs them. But in people with leukemia, the bone marrow produces an excessive amount of abnormal white blood cells, which dont function properly. The cause of leukemia is not fully understood, but it seems to develop from a combination of genetic and environmental factors. Treatment for leukemia can be complex and depends on the type of leukemia and other factors. Symptoms of leukemia can include fatigue, weakness, frequent infections, fever, weight loss, and easy bleeding or bruising.