Hydrochloric acid (HCl) is a highly versatile and widely used strong acid, primarily applied as a pH adjuster across multiple industries. Commercial hydrochloric acid is typically available in concentrations ranging from 30% to 37% and is a clear, corrosive liquid with a pungent, irritating odor. Its primary role in pH adjustment lies in its ability to donate hydrogen ions (H⁺), rapidly lowering the alkalinity of water and process solutions. In water treatment, it is employed to control pH, regenerate ion-exchange resins, and maintain process stability. Beyond water treatment, hydrochloric acid plays an essential role in the chemical industry for the production of chlorides, fertilizers, dyes, and pharmaceuticals, while in the food industry, it is used for processing and acidity regulation. Its strong corrosive nature necessitates the use of acid-resistant materials for storage and strict safety measures during handling, as direct contact causes severe burns and fumes are harmful if inhaled. Hydrochloric acid is easily neutralized with bases like sodium hydroxide or lime, making it practical for controlled applications. With its wide availability, low cost, and high effectiveness, hydrochloric acid continues to be a critical chemical in global industrial operations, especially for maintaining precise pH balance in sensitive systems.