text: Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid.
  Urea serves an important role in the cellular metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. Urea is Neo-Latin, , , itself from Proto-Indo-European *h₂worsom.
  It is a colorless, odorless solid, highly soluble in water, and practically non-toxic ( is 15 g/kg for rats). Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, most notably nitrogen excretion. The liver forms it by combining two ammonia molecules () with a carbon dioxide () molecule in the urea cycle. Urea is widely used in fertilizers as a source of nitrogen (N) and is an important raw material for the chemical industry.
  In 1828, Friedrich Wöhler discovered that urea can be produced from inorganic starting materials, which was an important conceptual milestone in chemistry. This showed for the first time that a substance previously known only as a byproduct of life could be synthesized in the laboratory without biological starting materials, thereby contradicting the widely held doctrine of vitalism, which stated that only living organisms could produce the chemicals of life.