A deviated nasal septum (DNS) is a condition characterized by deviations in the nasal septum, which can be caused by trauma, developmental defects, and genetic factors. It presents with various clinical features, including nasal obstruction, pressure headaches, reduced sense of smell, and increased risk of infections. Treatment options range from observation for mild cases to surgical interventions like submucous resection or septoplasty for more severe cases requiring correction of the obstruction.