Friction stir welding, a solid state joining process is an already proven technique for the welding of metals. Lately, it has been employed on polymers, which also have shown efficacious joining results. Due to recent consideration of this process on polymers, a limited body of literature on friction stir welding of polymers exists. This paper presents an overview of the state-of-the-art of the process on similar and dissimilar polymers. The process parameters which are significant for weld strength and various approaches to maximize it, such as external heat induction, tool modification, and material flow are central to this discussion. Finally, the conclusions drawn with future recommendations are reflected as well.