Define lattice enthalpy. How is it relate to the stability of an ionic compound?

The lattice enthalpy (lattice energy) of an ionic solid is defined as the enthalpy required to completely separate one mole of a solid ionic compound into gaseous constituent ions. e.g. the lattice enthalpy of NaCl is 788 kJ mol^–1. This means that 788 kJ of enthalpy is required to separate an infinite distance 1 mol of solid NaCl into 1 mol of Na⁺ (s) and one mole of Cl^– (g).
The greater the lattice enthalpy, more stable is the ionic compound.