A fever is when your body temperature rises above the normal range, usually around 98.6°F (37°C). This increase often happens when your body is fighting off an infection, like a cold or the flu. The rise in temperature is a natural response that helps your immune system work better to combat germs and viruses. When you have a fever, you might feel hot, sweaty, or even shivery. It's important to stay hydrated and rest. If the fever is very high or lasts for a long time, it’s a good idea to consult a doctor, especially for children or the elderly, as they may need special care.