Urea is white and odorless which is highly soluble in water. Urea is derived mainly from natural gas and petroleum feedstocks, making it a petrochemical product. 

Urea is widely known as carbamide, The diamide form of carbonic acid. Urea is popularly useful as a fertilizer, a feed supplement, and a starting material to manufacture drugs and plastics. It is a colourless substance that exists in the crystalline form. It melts at 132.7∘C  and decomposes before the boiling point of urea. The chief and product of metabolic protein Break down in few fishes and all the major mammals is urea.

Urea-SCR, the selective catalytic reduction using urea as reducing agent, has been investigated for about 10 years in detail and today is a well established technique for DeNOx of stationary diesel engines. It is presently also considered as the most promising way to diminish NOx emissions originating from heavy duty vehicles, especially trucks.