Filamentary plasma structures are ubiquitous to the plasma edge region of magnetically confined fusion plasma devices, like tokamaks and stellerators. They are known carriers of large particle densities and currents. The formation of these structures is currently thought to be a result of drift-based instabilities that interact to form local perturbations of the plasma pressure that are aligned with the magnetic field lines. The eventual interactions between cross-field transport and parallel transport in the edge play a role in determining the dynamics of these structures, particularly in the scrape-off layer (SOL). Filamentary motion, i.e. after they are already formed, is largely driven by the E × B drift. But their formation per se is not completely understood. Nonetheless we are able to gain some insight into possible triggers by parametric studies using simulations. Their detailed characterisation has been the focus of recent studies to try and better understand this topic in a growing effort to keep the plasma-wall interactions within permissible limits. This has strong implications for the success and durability of the first wall and divertor surfaces in a potential commercial fusion reactor.