Solution plasmas usually refer the plasmas in liquids. Either plasma in gas or in liquid, they are electrical discharge. Therefore, they are believed to share fundamentals, including molecular interaction (e.g., attractive and repulsive forces between molecules), breakdown, propagation, and formation of plasma layers, referring to plasma sheath. However, due to density of media, plasma in liquid has the altered characteristics, compared to that of plasma in gas. Accordingly, the clear understanding of plasmas in liquid, like solution plasma, should be explained and applied, aiming to maximize the benefit of plasma technology. In this chapter, the general explanation relating to the definitions and basic fundamental relating to SP is provided.