A tumor is an abnormal growth of cells in the body. These cells can multiply uncontrollably, forming a lump or mass. Tumors can be classified as benign, which are non-cancerous and usually do not spread, or malignant, which are cancerous and can invade nearby tissues or spread to other parts of the body. The causes of tumors can vary, including genetic factors, exposure to certain chemicals, or lifestyle choices. Early detection is important for effective treatment, which may involve surgery, radiation, or chemotherapy. Understanding tumors helps in the fight against diseases like cancer and improves patient outcomes.