An ulcer is a sore, open place where the surface has broken down and will not close up quickly. It can be on your skin — an ulcer on the leg of someone whose blood does not flow well — or inside your body, most commonly in the stomach or the first part of the small intestine, where doctors call it a stomach ulcer or a peptic ulcer. It can bleed, and it usually hurts. The everyday small kind is the mouth ulcer, the little white sore inside your cheek or lip that stings when you eat something salty; British English says "mouth ulcer" and American English usually says "canker sore" for the same thing. English also uses the word loosely, as a joke about worry — "this job is giving me an ulcer" means the stress is eating me alive. That joke sits on an old belief that stress and spicy food cause stomach ulcers. Doctors now know most stomach ulcers come from a bacterium called H. pylori or from long use of painkillers like aspirin, and can be cured with antibiotics — a discovery that won a Nobel Prize in 2005. Stress can make an existing ulcer feel worse, but it is not usually the cause.