Rectifying or rectification refers to the process of multiple subsequent distillations resulting in increasingly purified spirit or distillate. Typically for ethanol this process is industrial as the number of evaporation & condensation steps required are significant resulting in very tall columns being required to obtain the desired purity. Ethanol has similar properties to water and as such they form an azeotrope at ca. 96% ethanol, which is more stable than pure ethanol, and thus the maximum purity that can be obtained via distillation without using additives or other methods to break the azeotropic limit.