Porous networks represent a class of materials with interconnected voids with specificproperties concerning adsorption, mass and heat transport, and spatial confinement, which lead toa wide range of applications ranging from oil recovery and water purification to tissue engineering.Porous networks with well-defined, highly ordered structure and periodicities around the wavelengthof light can furthermore show very sophisticated optical properties. Such networks can be fabricatedfrom a very large range of materials by infiltration of a sacrificial colloidal crystaltemplate and subsequent removal of the template. The preparation procedures reported in the literatureare discussed in this review and the resulting porous networks are presented with respect to the underlyingmaterial class. Furthermore, methods for hierarchical superstructure formation and functionalizationof the network walls are discussed.