The energetics of point defects provide the controlling factor in determini
ng the atomistic mechanisms in a wide range of solid state processes. We pr
esent here a pedagogical overview of the development of the continuum, quas
i-lattice and lattice theories for different classes of point defects and m
aterials. Varied approaches were followed in the past in modelling the rele
vant perfect crystals for interatomic forces for nonionic solids and model
potentials for ionic materials. The earliest continuum approaches are those
of Eshelby and Jest for treating point defects as elastic and dielectric s
ingularities. These were followed by semicontinuum Mott-Littleton technique
s and the Kanzaki defect force techniques in application to charged and neu
tral defect species. However the importance of a correct assessment of the
dielectric polarization and the anharmonicity of the forces in the evaluati
on of the enthalpies and volumes have been well documented. Numerical compu
tations of the enthalpies are seen to be sensitive to the choice of potenti
al parameters and polarization models to varying degrees. While the theoret
ical picture is relatively clear in the case of the simpler materials with
a near-ideal pure disorder, materials with mixed type of point defect disor
ders call for a more challenging simulation of defect environments which am
ong other things should take into account the strong inhomogeneities of def
ect fields. The paper gives an overview of the evolution covering the highl
ights of these developments.