A column (or tower) is a vertical industrial vessel designed for mass transfer, heat exchange, or chemical reactions, widely used in industries such as petroleum refining, chemical processing, and environmental engineering. Common types include distillation columns (separating liquid mixtures via boiling points), absorption columns (removing gas components using solvents), extraction columns (liquid-liquid separation), and adsorption columns (purifying streams with adsorbents like activated carbon). Key components comprise the shell, internals (trays/packings), reboiler, condenser, and control systems. Columns operate under precise temperature, pressure, and flow conditions to maximize efficiency while avoiding issues like flooding or weeping. Advanced designs employ structured packings and automation to optimize performance in applications ranging from crude oil fractionation to CO₂ capture.