Ionic fluids, e.g. charged colloids, electrolyte solutions, room temperature ionic liquids, fused salts, polyelectrolytes and gas plasmas, are multi-component complex fluids with the constituent particles interacting via Coulomb forces. Whereas the Coulomb interaction between two particles is long-ranged, i.e. it decays with a power-law potential, screening renders charge-charge correlations short-ranged, i.e. exponentially decaying. Therefore, besides the particle size and the bulk correlation length, the screening length occurs as an additional relevant length scale in ionic fluids. In order to understand the consequences of this increased complexity due to electric charges of ionic fluids we use liquid state theoretical methods and computer simulations to investigate the phase behaviour, bulk and interfacial structures as well as dynamic properties.