A solid substance is characterized by having a spatial structure consisting of a three-dimensional lattice at whose vertices the atoms are located. Because the atoms are in continuous motion due to thermal agitation, the vertices of the lattice are defined, more properly, as the equilibrium positions around which the atoms vibrate. This structure gives to the solid the rigidity that opposes not only the compression and stretch but also shear. In other words, offering resistance to the volume and shape changes. The spatial structures can be ordered as those of the crystalline solid or disordered such as those of the amorphous solids and glasses.