Strep throat is a bacterial infection caused by the Streptococcus pyogenes bacteria. It primarily affects the throat and tonsils, leading to symptoms such as a sore throat, difficulty swallowing, and swollen lymph nodes. It is more common in children but can affect people of all ages. The infection is spread through respiratory droplets when an infected person coughs or sneezes. Diagnosis typically involves a throat swab, and treatment usually includes antibiotics to reduce symptoms and prevent complications. If left untreated, strep throat can lead to more serious conditions, such as rheumatic fever.