Tonsillitis is an inflammation or infection of the tonsils caused by bacteria or viruses. The tonsils are located in the throat and are part of the immune system, fighting infections that enter the body through the mouth or nose. Symptoms include a sore throat, difficulty swallowing, and fever. Diagnosis involves examination for swollen tonsils and testing of throat secretions. Treatment focuses on relieving symptoms with medication and antibiotics if bacterial infection is detected. Complications can include abscesses, though tonsil removal may be required for repeated cases. Prevention involves good hygiene and avoiding contact with other sick individuals.