Multiple myeloma is a cancer of plasma cells in the bone marrow, characterized by abnormal cell growth leading to tumors in bones, bone pain, fractures, weakness, and fatigue. Symptoms may include frequent infections, thirst, and urination. Diagnosis involves lab tests and imaging, with treatment options such as chemotherapy, stem cell transplantation, radiation, or targeted therapy. The disorder can cause anemia, weakened immune system, kidney problems, and hypercalcemia. It is more common in older individuals, African Americans, and those with a family history of the condition.