Strictures are abnormal narrowing of a tubular structure in the body, often resulting from inflammation, scarring, or disease processes such as Crohn's disease or cancer. They are clinically significant as they can lead to obstruction, impaired function, and complications like pain, infection, or perforation, necessitating timely diagnosis and management. An example is esophageal strictures, which can cause dysphagia and require interventions like dilation or surgery.