Sodium hypochlorite (NaClO) and its active ingredient, hypochlorous acid (HClO), are the most widely used chlorine-based disinfectants. HClO is a fast-acting antimicrobial that interacts with many biomolecules, including amino acids, lipids, nucleic acids, and sulfur containing membrane components, causing cell damage. In this review, we present examples of the effectiveness of chlorine in general disinfection procedures to inactivate bacteria and, under some conditions, bacteria in biofilms and viruses.