Urea is a crystalline chemical that lacks color and melts at 271 degrees Fahrenheit. It is found in all mammals as a biological byproduct. Due to its nitrogen content, urea is often used in fertilizers and animal feed and is very useful for plants and farming.
While urea is found in urine, it is also expelled from many other places of the body due to the prevalence of the substance throughout mammalian biology. It's produced from the ammonia produced during the breakdown of proteins, with the liver converting it from more harmful ammonia molecules into the less dangerous urea which is then expelled from the body.
A related compound known as uric acid is expelled from some reptiles and birds, as well as humans. In humans, it is generated in small amounts compared to other waste products, and if it builds up, can cause issues such as gout, which involves the development of salt in bone and cartilage.
Urea was the first accepted organic compound to be synthesized from inorganic compounds. As a result of the ability to synthesize it, methods of synthesis were developed using liquid ammonia and liquid carbon dioxide, allowing for the creation of very large quantities of urea for use in farming and more.