Meat is animal tissue, often muscle, that is eaten as food. Humans have hunted and farmed other animals for meat since prehistory. The Neolithic Revolution allowed the domestication of vertebrates, including chickens, sheep, goats, pigs, horses, and cattle, starting around 11,000 years ago. Since then, selective breeding has enabled farmers to produce meat with the qualities desired by producers and consumers.
Meat is mainly composed of water, protein, and fat. Its quality is affected by many factors, including the genetics, health, and nutritional status of the animal involved. Without preservation, bacteria and fungi decompose and spoil unprocessed meat within hours or days. Under optimal conditions, meat is edible raw, but is often normally eaten cooked—such as by stewing or roasting—or processed—such as by smoking or salting.
The consumption of meat (especially red and processed meat) increases the risk of certain negative health outcomes including cancer, coronary heart disease, and diabetes. Meat production is a major contributor to environmental issues including global warming, pollution, and biodiversity loss, at every scale from local to global. Some people choose not to eat meat (vegetarians and vegans) for reasons such as ethics, environmental effects, health concerns, or religious dietary rules. However, meat is important to economies and cultures around the world.