|An ulcer is a sore or lesion that develops in the tissue lining of the stomach or duodenum. The stomach produces stomach acids such as pepsin and hydrochloric acid to digest the food. If these stomach acids and digestive juices injure and corrode the stomach’s lining of protective mucus, then an ulcer may form. Ulcers in the stomach are known as stomach or gastric ulcers while those found in the duodenum are called duodenal ulcers. They can develop at any age, but are generally uncommon amongst children and teenagers. Stomach ulcers tend to affect people over the age of 60, particularly more women than men.