Acid-Base Theory explains how substances interact based on their ability to donate or accept protons (H⁺ ions). According to the Brønsted-Lowry theory, acids are proton donors, while bases are proton acceptors. This theory helps us understand various chemical reactions, including neutralization, where an acid and a base react to form water and a salt. Another important perspective is the Lewis theory, which defines acids as electron pair acceptors and bases as electron pair donors. This broader definition allows for a wider range of chemical interactions, including those that do not involve protons, enhancing our understanding of chemical behavior in different environments.