What is distillation, and what is the principle behind it?

The basic principle of distillation is to take advantage of the different volatilities of the various components in a mixture. The material is heated at the bottom of the distillation tower, generating rising vapor; this vapor comes into thorough countercurrent contact with the reflux liquid that condenses at the top of the tower within the tray sections, allowing for mass and heat transfer. As a result, the more volatile components vaporize and enter the gas phase, while the less volatile components condense and enter the liquid phase. This process is repeated multiple times to ensure that all components in the mixture are fully separated. The process by which a liquid mixture is partially vaporized multiple times, while the resulting steam is also partially condensed multiple times, in order to separate it into the desired components, is called distillation.