Distillation is a separation process used to purify liquids by heating them to create vapor and then cooling the vapor to obtain a liquid. This technique exploits differences in boiling points between components in a mixture, allowing the more volatile substances to evaporate first. The vapor is then condensed back into a liquid, resulting in a more concentrated and purified product. Distillation is commonly used in industries such as petrochemical refining, alcohol production, and water purification.