Hygiene, defined as practices preventing infection transmission, is vital for public health, especially highlighted during outbreaks like SARS and avian influenza. Key focuses include handwashing, household cleaning, food safety, and respiratory etiquette. Studies in developing countries show handwashing reduces diarrheal diseases (30–47% risk reduction), while U.S. trials found alcohol-based sanitizers cut gastrointestinal illnesses but not respiratory ones. However, antibacterial products showed no added benefit, and improved handwashing in schools didn’t lower absenteeism. Overzealous hygiene poses risks: skin irritation from harsh agents, potential asthma links to irritants like bleach, and the "hygiene hypothesis" tying excessive cleanliness to allergies. Antibacterial overuse may also drive resistance. Recommendations emphasize handwashing with soap, alcohol sanitizers where water is scarce, avoiding routine antibacterial cleaners, and skin protection with lotions. Respiratory hygiene remains commonsense but unproven.