The bond order of individual carbon bonds in benzene is

 The bond order of individual carbon-carbon bonds in benzene is between one and two. It is due to resonance structure of ${\mathrm{C}}_6{\mathrm{H}}_6$. In the benzene molecule, carbon atoms form a ring with alternating single and double bonds in between each of them. Each carbon atom forms one bond with one carbon atom and one bond with another. The bonding electrons are delocalized over the entire molecule. Thus, benzene is a resonance hybrid of two equivalent structures, and the single and double bonds oscillate from one position to the other.