This chapter describes the main components of the polymer electrolyte fuel cell and its role in cell performance. It presents five synthesis routes for the preparation of electrocatalysts, and discusses the influence of nanoparticle formation on the catalytic properties. Regarding the polymer electrolyte membranes, the chapter explains proton transport within membranes based on their structural features. Physicochemical and transport properties characterizing the membranes are described as well. The chapter further highlights the importance of bipolar plates in general, the selection of suitable bipolar plate materials, and different flow-field designs.