Explain how crude oil gets separated into its components

Crude oil is a mixture of hydrocarbons with varying length carbon chains. The main method used to separate these is fractional distillation. The crude oil is heated, then placed inside a fractionating column, which has a temperature gradient (it is hot at the bottom and cool at the top). The majority of the fractions are in vapour form and as they travel up the fractionating column, they condense at the appropriate temperatures and are distilled off as their individual fractions. The hydrocarbons with the highest boiling points stay near the bottom whereas the ones with the lower boiling points rise to the top. The really heavy hydrocarbons remain as liquids at the bottom of the column.