Resistance seam welding (RSEW) is a process in which the heat generated by resistance to the flow of electric current in the work metal is combined with pressure to produce a welded seam. This article discusses the various classes of the RSEW process, namely roll spot welding, reinforced roll spot welding, and leak-tight seam welding. It provides information on the applications of lap seam weld, mash seam weld, and butt seam weld. The article reviews the advantages and limitations of seam welding compared to resistance spot welding, projection welding, and laser welding. It describes the four basic types of resistance seam weld machines: circular, longitudinal, universal, and portable. The article concludes with a discussion on weld quality and process control for seam welding.