Nosocomial infections, also known as hospital-acquired infections, occur in patients during or after hospital treatment. In the US, over 1.7 million nosocomial infections occur annually, resulting in 99,000 deaths. In India, the rate of nosocomial infections is over 25%, affecting 1 in 4 hospital patients. Common sources of nosocomial infections include contaminated air, water, medical equipment, and hospital waste. Prevention strategies focus on proper hand hygiene, sterilization of medical equipment, and vaccination of at-risk patients.