Condensed milk, also known as sweetened condensed milk, is
cow's milk from which
water has been removed and to which
sugar has been added, yielding a very thick, sweet product that can last for years without refrigeration if unopened. The two terms, condensed milk and sweetened condensed milk, have become synonymous; though there have been unsweetened condensed milk products, today these are uncommon. Condensed milk is used in numerous dessert dishes in many countries.
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A preserved milk in which the water content of the milk is evaporated and a lot of sugar is added. It was very popular in wartime England because of how well it preserved. These days it is used mainly in sweets and confectionery making. It is also used in iced drinks (Thai iced tea) because of its high sugar content (it won't freeze easily).