Lewis acids and Lewis bases are concepts in chemistry that describe how substances interact through electron pairs. A Lewis acid is a substance that can accept an electron pair, while a Lewis base is one that can donate an electron pair. This definition expands the traditional understanding of acids and bases beyond just protons. In a Lewis acid-base reaction, the Lewis base donates its electron pair to the Lewis acid, forming a coordinate covalent bond. This interaction is important in various chemical processes, including catalysis and the formation of complex ions, highlighting the versatility of acid-base chemistry.