Cosmological consequences of f(R) gravity

In this thesis, we are focusing on a theory called f(R) gravity, obtained from modifications of General Relativity (GR) by adding higher powers of the Ricci scalar into the standard GR action. By introducing additional terms to the action, we aim to replicate the observed evolution of the Universe without being hindered by the problems of the existence of dark matter and dark energy and address some other interesting phenomena in the universe such as gravitational waves and cosmological perturbations.