Cow dung is the faeces of the bovine species. The species includes the cow, buffalo, ox and bullock. Cow dung is used as manure in many parts of the developing world especially India where it is known as gobar. Cow dung is basically the rejects of herbivorous matter which is acted upon by symbiotic bacteria residing within the animal's rumen . The resultant faecal matter is a rich in minerals. Colour ranges from greenish to blackish. In due course of time, the resulting matter turns yellow due to chemical changes in the sunlight.

Cow dung is used primarily as a fertiliser. In recent times, the dung is collected and used as bio-gas which is used to generate electricity and heat. The gas is a rich source of methane and is used in rural areas of India to provide a renewable, stable and environment friendly source of electricity. Caked Cow dung is also used as a fuel to cook food in many parts of Asia and Africa.

Cow dung is also used to line the flooring and walls owing to its insect-repellent properties. In cold places, cow dung is used to line the walls of rustic houses as it proves to be a superior and cheap insulator. Cow dung has an excellent mosquito repellent property and is used by many companies to produce repellents. It was also used extensively on Indian Railways to seal smokeboxes on steam locomotives.