Electrophilic substitution reaction takes place in benzene and its derivatives, because Pi electron cloud perpendicular to the plane of benzene is positive loving or nucleophile. If the functional group present with benzene ring is electron withdrawing then electrophile will attack at “meta” position and if the functional group is electron donating then the electrophile will attack at “Ortho” and “Para” position. Reactivity towards electrophilic substitution depends on the nature of functional group attached, as the electron donation power of functional group increases reactivity towards electrophilic substitution increases and as the electron withdrawing power increases the reactivity towards electrophilic substitution decreases.