Polymer Electrolyte Fuel Cells (PEFCs) are one of the possible energy sources for the near future energy systems. The advantages of PEFC power generation are one of the most effective energy conversion systems and gentle in our environment. In addition, PEFC attracts huge interests as power supply systems for portable electric devices, residential power generation systems and electric vehicles. This article introduces here the comparison of several different types of Fuel Cells, their mechanisms and up-to-date research and developing stages for PEFC.