A respiratory infection is an illness that affects the nose, throat, and lungs. It can be caused by viruses, such as the common cold or influenza, or by bacteria. Symptoms often include coughing, sneezing, sore throat, and difficulty breathing. These infections can range from mild to severe and may require medical attention. Most respiratory infections are contagious and can spread through the air or by touching contaminated surfaces. Prevention methods include regular handwashing, avoiding close contact with sick individuals, and getting vaccinated against certain viruses, like the flu and COVID-19.