Desalination provides a sustainable source of fresh water for countries with limited water resources. Progress in the desalination technology made highly competitive to water transportation over long distances. Also, desalination is less harmful to the environment than water dams, which results in severe environmental problems up and down stream. At present the desalination industry is dominated by the reverse osmosis (RO) and the multistage flash desalination (MSF) processes. Other thermal desalination processes, which include the multiple effect evaporation (MED) and the mechanical vapor compression process (MVC) are found on a much limited scale. Features of the three thermal desalination processes are discussed with focus on design, energy, and economic aspects. Design features include performance ratio, specific heat transfer area, and system dimensions.