Fractional distillation is a process used to separate mixtures of liquids with different boiling points by heating the mixture and then separating the vaporized components based on their boiling points. As the vapors rise in a fractionating column, they condense at different heights and can be collected separately, leading to the purification of the components. This technique is commonly used in the petroleum industry to separate crude oil into various components such as gasoline, diesel, and jet fuel.