Cancer is a broad term for diseases characterized by the uncontrolled growth of abnormal cells. There are over 100 different types of cancer, which are typically classified based on the organ or type of cell where they originate. Common types include breast cancer, lung cancer, prostate cancer, and colorectal cancer. Each type can have distinct characteristics, symptoms, and treatment options. Cancers are also categorized into groups such as carcinomas, which arise from epithelial cells, and sarcomas, which originate in connective tissues like bones and muscles. Other categories include leukemias, cancers of the blood, and lymphomas, which affect the lymphatic system. Understanding these types helps in diagnosing and treating cancer effectively.