Steam

Steam is what water turns into at a temperature of 100 °C (212 °F), as explained under boil, and to steam foods is to cook them in this steam at that temperature in (necessarily) a lidded recipient.

This method of cooking has certain advantages. The food will not be bumped about by the agitation of boiling, or even simmering, water; and loss of water-soluble vitamins is less than when the food is immersed in boiling water. For this last reason, steaming vegetables is recommended. However, there are many other uses for the technique, for example steaming couscous in the upper part of a couscous steamer, while other ingredients (meat, vegetables) which will go into the finished dish are boiled in the lower part. Also, several dishes can be steamed at once, stacked in tiers above a pan of boiling water, a technique which has been exploited by the Chinese, of whose cookery steaming is a fundamental feature.