Introduction to the microstructural dependence of properties; introduction to, and perspective on, the porosity dependence of properties; porosity dependence of elastic properties at low to moderate temperatures; porosity dependence of fracture energy and toughness, and related crack propagnation at 22C; porosity dependence of tensile strength and reliability at low to moderate temperatures; porosity dependence of hardness, compressive strength, wear and related properties at low to moderate temperatures; porosity dependence of thermal and electrical conductivities and other nonmechanical properties at low to moderate temperatures; porosity dependence of mechanical and other physical properties of related materials at 22C; porosity dependence of properties at higher temperatures, including effects of porosity on thermal shock; summary of porosity dependence, NDE, applications and engineering of porous ceramics.