A reaction that occurs when acids and bases neutralize each other is called a neutralization reaction. During this process, an acid reacts with a base to produce water and a salt. The characteristic of acids is the presence of hydrogen ions (H+), while bases contain hydroxide ions (OH-). When they combine, H+ and OH- ions react to form water (H2O), thus reducing the acidity and basicity of the original substances. Neutralization reactions are fundamental in chemistry and play a critical role in various biological and industrial processes.