A Brønsted base is a substance that can accept protons (H⁺ ions) in a chemical reaction. This concept is part of the Brønsted-Lowry theory of acids and bases, which defines acids as proton donors and bases as proton acceptors. When a Brønsted base accepts a proton, it forms its conjugate acid. Common examples of Brønsted bases include substances like ammonia (NH₃) and sodium hydroxide (NaOH). These bases can react with acids to form water and salts, playing a crucial role in various chemical processes, including neutralization reactions and biological systems.