Chapter one provides an introduction, examples of application areas and background information. Chapter two deals with the primary material properties for the areas of application and lists the possible constituent parts of the composites, depending on particular demands. Chapter three explains both the past and present fabrication methods which can affect the performance of the composites. Chapter four defines the interphase-related phenomena and describes the mechanical characteristics of the oxide-based fiber-reinforced composite, produced with different interphases. Chapter five deals with the fabrication route, functionality and mechanical characterization of the porous-matrix composites. The last chapter summarizes the present achievements and identifies requirements for reaching the goal, thereby providing a promising course for future research.