Infections occur when harmful microorganisms, such as bacteria, viruses, or fungi, invade the body and multiply. This can lead to various health issues, ranging from mild illnesses like the common cold to severe diseases such as HIV/AIDS or tuberculosis. Understanding how infections spread and how the immune system responds is crucial for prevention and treatment. Preventing infections often involves good hygiene practices, vaccinations, and proper sanitation. When infections do occur, they can be treated with medications like antibiotics for bacterial infections or antivirals for viral infections. Early detection and treatment are key to managing infections effectively.