Ionic crystals are typically characterized by high melting points due to the strong electrostatic forces between the positively and negatively charged ions.
The attractive forces between oppositely charged ions are strong, requiring a significant amount of energy to overcome, resulting in high melting points.
When one atom loses an electron to form a cation and another atom gains that electron to form an anion, the resulting attraction between the oppositely charged ions is an ionic bond.
This type of bond is typically formed between a metal and a nonmetal, and is characterized by a transfer of electrons rather than a sharing of electrons (as in covalent bonds).