Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder that affects the large intestine. It is a functional disorder, meaning that it affects the way the intestine works, but does not cause any physical damage or changes to the structure of the bowel.

The symptoms of IBS can vary from person to person but typically include abdominal pain or discomfort, bloating, constipation, diarrhea or alternating constipation and diarrhea, gas, and mucus in the stool. These symptoms may be triggered or exacerbated by stress, certain foods, hormonal changes, or other factors.

The exact cause of IBS is not known, but it is thought to be related to abnormal contractions of the colon and increased sensitivity to certain stimuli. It is a common condition, affecting around 10-15% of adults in the Western world, and can be managed with lifestyle changes, dietary modifications, and medications to control symptoms.