What sort of disease is cholangitis?

Inflamed bile ducts. Cholangitis can be caused by bile duct inflammation from infections, blockage of ducts by stones, rarely by strictures ( benign or from cancer), it is also seen in patients with ulcerative colitis as primary sclerosing cholangitis. The treatment depends on the condition causing cholangitis.
Charcot's Triad. Cholangitis is an infectious inflammation of the bile circulation which in turn results in inflammation of the liver. The hallmark signs of cholangitis are known as "charcot's triad" and include: right upper quadrant abdominal pain, fever, and jaundice (yellowing of the skin). Cholangitis can be fatal if left untreated.
Bile Duct Infection. Chaolangitis occurs when a gallstone leaves the gallbladder and get stuck in the common bile duct, which normally drians bile into the small intestine. When a stone gets stuck, bile is unabel to drain and gets backed up, leading to an infection. Teh bile duct almost always needs to be cleared of stones - thsi is most commonly done by an endoscopy but can be done surgically.