Assertion (A): In sodium chloride ionic bond is present between sodium and chlorine ions. 

Reason (R):  In sodium chloride one electron is transferred from sodium to chlorine.

The electro static force of attraction between two ions or atoms by the transfer the electrons from one atom to another atom are called ionic bond.  Here sodium lose one electron to get ${\text{Na}}^{\text{+}}$ and Chlorine gains one electron from sodium and gets ${\text{Cl}}^{-}$.