The C-C bond, or carbon-carbon bond, is considered a nonpolar covalent bond. This classification is due to the fact that both atoms involved in the bond are carbon atoms, which have the same electronegativity.
Electronegativity is a measure of how strongly an atom attracts electrons in a bond. Since both carbon atoms have equal electronegativity, they share the electrons equally, which means there is no significant charge difference across the bond. Therefore, there is no dipole moment created, and the bond does not exhibit polar characteristics.
In summary, since the sharing of electrons is equal between the two identical carbon atoms, the C-C bond is nonpolar covalent.