Infections spread through a 'chain of infection': a pathogen source, a way to exit that source, a mode of transmission such as touch or airborne droplets, a way to enter a new host, and a susceptible person; breaking any one link stops the spread. Proper hand hygiene, using soap and water for at least 20 seconds or an alcohol-based sanitizer when hands aren't visibly dirty, is the single most effective and lowest-cost infection control measure available in any setting. Personal protective equipment (PPE), gloves, masks, gowns, and eye protection, should be selected based on the specific risk of exposure, put on and removed in the correct order to avoid self-contamination, and never reused in ways that defeat its purpose. These practices apply equally in hospitals, clinics, and home-care settings, and are especially critical when caring for patients with compromised immune systems.