Pharyngitis is the inflammation of the pharynx, which is the area at the back of the throat. It commonly causes a sore throat, pain when swallowing, and may accompany other symptoms like fever or swollen lymph nodes. Pharyngitis can be caused by viral infections, bacterial infections (such as streptococcus), or irritants like smoke and allergens. Treatment typically depends on the underlying cause, with viral infections often resolving on their own, while bacterial infections may require antibiotics.