In order to determine the deformation response of materials and structures subjected to external loading conditions, classical continuum mechanics (CCM) was introduced by disregarding the atomistic structure. CCM has been successfully applied to numerous challenging problems. However, its governing equation faced a difficulty when there is any discontinuity in the structure such as a crack, since spatial partial derivatives in its governing equation are not defined for such a condition.  In order to overcome this problem, a new continuum mechanics approach, Peridynamics (PD), was recently introduced with the intention that its governing equation is always valid whether there is any discontinuity in the structure or not. Moreover, PD can be considered as the continuum version of molecular dynamics. This character of PD makes this new approach a suitable candidate for multi-scale analysis of materials. Furthermore, PD formulation can also be extended to other fields such as thermal, moisture, etc., so that it can be used as a single platform for multiphysics analysis of materials.