Ulcerative colitis is a chronic inflammatory bowel disease (IBD) that causes inflammation and ulcers in the lining of the colon and rectum. The inflammation is continuous, typically starting in the rectum and extending upward through part or all of the colon. Symptoms often include persistent diarrhea, abdominal pain, rectal bleeding, urgency to have bowel movements, fatigue, and unintended weight loss. The exact cause is not fully understood but is believed to involve an abnormal immune response, genetic predisposition, and environmental factors. Ulcerative colitis follows a relapsing-remitting pattern, with periods of flare-ups and remission, and long-term inflammation can increase the risk of complications such as colon strictures or colorectal cancer.