An ionic bond is formed when an electron is essentially transferred from one atom of a pair to the other creating ions. Sodium chloride is an example of a compound with this type of bond. These compounds exist as a crystal lattice with all the ions stacked in definite patterns. The following picture is a representation of a cubic crystal of sodium chloride. The chloride ions are represented by the purple spheres.
Remember that a cation is a positively charged atom or molecule (one that has lost one or more electrons) and that an anion is a negatively charged atom or molecule (one that has gained one or more electrons). The ions are held together by electrostatic attractions. Ionic compounds have high melting points and many are soluble in water.