Finite Element Method FEM

السلام عليكم ورحمة الله
جئت متأخراً في هذا النقاش ولكني أود التنويه لنقطة مهمة وهي تحديد مجال تطبيق FEM الذي تتحدثون عنه لأن تطبيقاتها كثيرة
I use FEM and FDM for groundwater modelling. Most software use Galaerkin methods but the two main approaches are the Variational method and the Residual method. I like to learn about the basic idea of the FEM and how it has been evolved. As far a I know, it is based on minimization of energy principle.