Dielectric barrier discharges (DBDs) operating in a glow regime exhibit a variety of complex self-organized static or dynamical structures of filaments. Using a fluid model combined with fast camera diagnostics, we propose a clear physical description and explanation of the mechanisms responsible for the generation, annihilation, motion and self-organization of discharge filaments in DBDs in a glow regime. We show that low current “side discharges” generated during the same half-cycle in the vicinity of an isolated filament beyond the inhibition zone associated with charge spreading along the dielectric surface play an essential role in the triggering of these mechanisms.