Nature always offers astonishing shows to the humankind. Gravitational lensing is one of the most intriguing effects which can be observed, and the astrophysical applications of such a phenomenon span from particle physics ...

In this Thesis we report a general review of Extended Theories of Gravity and the fundamental aspects of General Relativity. We show the technicality of development of field equation with respect to Newtonian, Post-Newtonian ...