Bloating is a condition in which a person's abdomen swells up due to excess gas or fluid retention. It can be caused by various factors such as overeating, consuming certain types of foods, stress, hormonal imbalances, and medical conditions like irritable bowel syndrome (IBS) or celiac disease. Bloating can lead to discomfort, pain, and a feeling of fullness in the abdomen, even when there is no actual physical distension.