As it is known in Physics, two point-size charges (say two electrons) interact with each other through em forces. How this is happening? do they exchange photons? And if so, then do they exchange energy (carried by photons) at all time or in other words their interaction keeps on going forever?
According to quantum electrodynamics, the charged particles exchange virtual photons. These are not the same as real photons and the terminology has often caused confusion. In particular, one should not think of these virtual "photons" as streams of actual particles going from one charge to the other. The interaction definitely goes on forever, but this is not the same as some kind of eternal absorption and emission event.
Heuristically, the charged particles cause ripples in the EM field, which influence each other and cause the particles to interact. Some energy is also stored in the electromagnetic field, so the charges do exchange some of their energy with the field, but again, it is not helpful to think of this as some process happening over and over.
Thinking in terms of quantum fields interactions is very fundamental and more intutive than thinking in terms of particle interactions.
Two electrons interaction:
The vacuum is filled with electron and EM field fluctuating at zero vacuum expectation value(also other quantum fields except Higgs).These two electrons are nothing but localized excitations of elctron field at there respective spacetime points. This electron field due to these localized excitations create disturbances in the EM field, causing excitations in the EMF. These excitations in the EMF then travell to the opposite point to transfer the momenta & energy to the localized excitations of electron field, causing the overall effect of electron-electron repulsion.
Because the intermediate particles("photons" in this case) have no overall existence, we say these particles to be "Virtual Particles" (i.e, "virtual photon" in this case).