Cow dung, also known as cow pats, cow pies or cow manure, is the waste product of bovine animal species. These species include domestic cattle ("cows"), bison ("buffalo"), yak, and water buffalo. Cow dung is the undigested residue of plant matter which has passed through the animal's gut. The resultant faecal matter is rich in minerals. Colour ranges from greenish to blackish, often darkening soon after exposure to air.
Cow dung, which is usually a pale red colour (usually combined with soiled bedding and urine), is often used as manure (agricultural fertilizer). If not recycled into the soil by species such as earthworms and dung beetles, cow dung can dry out and remain on the pasture, creating an area of grazing land which is unpalatable to livestock.
In many parts of the developing world, and in the past in mountain regions of Europe, caked and dried cow dung is used as fuel.
Dung may also be collected and used to produce biogas to generate electricity and heat. The gas is rich in methane and is used in rural areas of India and Pakistan and elsewhere to provide a renewable and stable source of electricity.
In central Africa, Maasai villages have burned cow dung inside to repel mosquitos. In cold places, cow dung is used to line the walls of rustic houses as a cheap thermal insulator.
Cow dung is also an optional ingredient in the manufacture of adobe mud brick housing depending on the availability of materials at hand.
A deposit of cow dung is referred to in American English as a "cow pie," and in British English as a cowpat. Also known as "cow chips" when dry, it is used in the practice of "cow chip throwing" popularized in Beaver, Oklahoma in 1970. On April 21, 2001 Robert Deevers of Elgin, OK set the record for cow chip throwing with a distance of 185 feet 5 inches.
Cow dung provides food for a wide range of animal and fungus species, which break it down and recycle it into the food chain and into the soil.
In areas where cattle (or other mammals with similar dung) are not native, there are often also no native species which can break down their dung, and this can lead to infestations of pests such as flies and parasitic worms. In Australia, dung beetles from elsewhere have been introduced to help recycle the cattle dung back into the soil (see the Australian Dung Beetle Project and Dr. George Bornemissza)
Cattle have a natural aversion to feeding around their own dung. This can lead to the formation of taller ungrazed patches of heavily fertilized sward. These habitat patches, termed "islets", can be beneficial for many grassland arthropods, including spiders (Araneae) and bugs (Hemiptera). They have an important function in maintaining biodiversity in heavily utilized pastures 
A buffalo chip, also called a meadow muffin, is the name for a large, flat, dried piece of dung deposited by the American Bison. Well dried buffalo chips were among the few things that could be collected and burned on the prairie and were used by the Plains Indians, settlers and pioneers, and homesteaders as a source of cooking heat and warmth.
Bison dung is sometimes referred to by the name nik-nik. This word is a borrowing from the Sioux language (which probably originally borrowed it from a northern source). In modern Sioux, nik-nik can refer to the feces of any bovine, including domestic cattle. It has also come to be used, especially in Lakota, to refer to lies or broken promises (especially by the U.S. government), analogously to the vulgar English term "bullshit" as a figure of speech.