Classical electrodynamics (CED) and quantum electrodynamics (QED) are well established theories and have been tested experimentally in different regimes. However, there are still areas of CED and QED that deserve theoretical and experimental investigation. In view of the increasingly stronger available laser fields it is becoming feasible to employ them to test CED and QED under the extreme conditions supplied by ultra-intense fields. A fundamental problem in CED is the so-called radiation reaction problem: classically, when a charged particle (an electron, for definiteness) is accelerated by an external field, it emits radiation and this emission changes the motion of the electron. In the realm of CED, the so-called Landau-Lifshitz (LL) describes the motion of an electron by including the effects of radiation reaction and it has not yet been tested experimentally. We explore a new regime of parameters in which, as predicted by the LL equation, the influence of the radiation reaction on the electromagnetic spectra emitted by the electron is substantial. What is the quantum analog of radiation reaction? We have answered this question and have investigated the quantum radiation dominated regime, in which quantum recoil and radiation reaction effects both dominate the dynamics of the electron. Finally, QED predicts that electromagnetic fields can also interact in vacuum through charged virtual particles (vacuum fluctuations). By exploiting this pure quantum interaction, we have envisaged a matterless double-slit scenario consisting only of light. In the proposed scenario two separated, parallel laser beams form the slits that are probed by a third laser beam which is diffracted to generate an interference pattern entirely from light.