Bladder cancer occurs when abnormal cells grow in the lining of the bladder, an organ that stores urine. It is one of the most common types of cancer in the urinary system. Symptoms may include blood in urine, frequent urination, and pain during urination. There are several types of bladder cancer, with urothelial carcinoma being the most prevalent. Risk factors include smoking, exposure to certain chemicals, and chronic bladder infections. Early detection is crucial for effective treatment, which may involve surgery, chemotherapy, or immunotherapy.