Strep is a type of throat bacteria, specifically Streptococcus pyogenes, which is a common cause of sore throats and other infections. It is highly contagious and can be spread through contact with saliva or mucus from an infected person. Symptoms of strep throat include a sore throat, fever, swollen lymph nodes, and white patches on the tonsils. Treatment typically involves antibiotics to reduce the severity and duration of symptoms.