The purpose of this book chapter is to provide general information regarding microbial fuel cell (MFC) systems, an important type of fuel cell of environmentally friendly energy conversion systems as an alternative to fossil fuel technologies. Besides, it is one of the main motivations of this study to include the academic literature on microbial fuel cells, which is a very popular field of study in recent years. In this context, the history, principles, and different approaches of MFCs are discussed. After that, the materials (anode, cathode, membrane, etc.) that make up the system are examined. Finally, different types of microbial fuel cells that can be varied by material design are discussed and presented.