What is stoichiometric defect? State its types.

(N/A) stoichiometric defect is a point defect in a crystal lattice that does not disturb the stoichiometry of the solid. These are also known as intrinsic or thermodynamic defects.
They are primarily classified into two types for non-ionic solids:
$(i)$ Vacancy defect
$(ii)$ Interstitial defect
For ionic solids,these defects are classified as:
$(i)$ Schottky defect
$(ii)$ Frenkel defect