Benzene undergoes substitution reaction whereby one or more hydrogen atoms on the benzene ring is/are replaced by other atoms or groups of atoms. E.g CH\(_3\), OH, NO\(_2\), NH\(_2\) etc can be substituted to replace hydrogen atom. Substitution reaction is a reaction where one functional group is exchanged for another. There are several types of substitution reactions, including nucleophilic, electrophilic, and free radical. A substitution reaction is more peculiar to benzene compared to an addition reaction; benzene primarily undergoes substitution reactions because addition reactions would disrupt its stable aromatic ring structure, causing it to lose its unique stability due to delocalized electrons.