Modified gravity is a class of theoretical models that propose modifications to Einstein's General Relativity to describe gravitational phenomena. This research field investigates discrepancies between observations on astrophysical and cosmological scales and predictions from General Relativity, often by altering the gravitational Lagrangian or introducing new degrees of freedom. Its significance lies in offering alternative explanations for phenomena typically attributed to dark matter and dark energy, thereby probing the fundamental nature of gravity and spacetime.