As the number of distributed energy resources are being rapidly grown in the distribution network, many discussions over local markets to coordinate these emerging technologies are flown around. Thus, this chapter aims to investigate the concept of local energy markets (LEMs) from several perspectives. The concept of LEMs is first introduced, then the benefits and challenges of LEMs implementation are investigated. Since, LEM should be merged into existing market structure, the interaction among two market structures is discussed. As Blockchain-based LEM is drawn enough attention nowadays, the benefits, and challenges of such implementation are covered and eventually some LEM projects around the globe are introduced. We have collected the gaps to be bridged in the future in the concept of LEM at the end of this chapter.