-SO₃H, known as a sulfonic acid group, is a functional group characterized by a sulfur atom bonded to three oxygen atoms and one hydrogen atom. This group is highly polar and soluble in water, making it an important component in various chemical reactions. Sulfonic acids are often used in the production of detergents, dyes, and pharmaceuticals due to their ability to enhance solubility and reactivity. The presence of the -SO₃H group in organic compounds can significantly alter their properties. For example, compounds containing this group, such as benzenesulfonic acid, exhibit strong acidic behavior and can act as excellent catalysts in chemical processes. Additionally, sulfonic acids are utilized in the synthesis of ion exchange resins and surfactants, which are essential in many industrial applications.