Influenza, also known as the flu, is a sickness that makes people feel very tired and sick. It can cause symptoms like fever, cough, stuffy or runny nose, and body aches. The flu is caused by tiny germs called viruses. These viruses can be passed from one person to another by sneezing, coughing, or touching contaminated surfaces. To stay healthy and prevent getting the flu, it’s important to wash your hands often and cover your mouth and nose when you sneeze or cough. You can also get a special shot called a flu vaccine that can protect you from getting sick.