Domestic sheep are relatively small ruminants, usually with a crimped hair called wool and often with horns forming a lateral spiral. Depending on the breed, domestic sheep may have no horns at all or horns in both sexes, or in males only. Colors of domestic sheep range from pure white to dark chocolate brown, and even spotted or piebald. Sheep have an excellent sense of smell and have scent glands just in front of the eyes and on the feet. These animals have horizontal slit-shaped pupils, with excellent peripheral vision. With visual fields of about 270° to 320°, sheep can see behind themselves without even turning their heads.
Domestic sheep are found worldwide in association with humans. They live in different habitats ranging from mountain forests to desert conditions.
Domestic sheep are diurnal flock animals. They do not defend territories although they do form home ranges. All sheep usually congregate close to other members of a flock, and they can become stressed when separated from their flock members. During flocking, sheep have a strong tendency to follow, and a leader may simply be the first individual to move. Sheep establish a dominance hierarchy through fighting, threats, and competitiveness. Dominant animals are more aggressive with other sheep and usually, feed first at troughs. When threatened, these animals usually flee from danger. Cornered sheep or females with newborn lambs may charge and butt, or threaten by hoof stamping and adopting an aggressive posture. Sounds made by domestic sheep include bleats, grunts, rumbles, and snorts. Bleating ("baaing") is used mostly for contact communication but also may signal distress, frustration or impatience. When in pain sheep are usually silent.
Domestic sheep are polygynous and a group of females is generally mated by a single male. They are seasonal breeders, although some are able to breed throughout the year. In feral sheep, males may fight during the rut (mating season) to determine which individuals may mate with females. Females usually give birth to a single lamb or sometimes twins. The gestation period usually lasts around 5 months. Newborn lambs are able to stand within an hour after birth and shortly after that start nursing. Young females usually become reproductively mature at six to eight months of age, and males - at four to six months of age.
Domestic sheep are most likely descended from the wild mouflon of Europe and Asia. Sheep are one of the earliest animals that were domesticated for agricultural purposes. They are raised for fleeces, meat (lamb, hogget or mutton) and milk. A sheep's wool is the most widely used animal fiber and is usually harvested by shearing. Sheep meat is called lamb when from younger animals and mutton when from older ones in Commonwealth countries, and lamb in the United States (including from adults). These animals continue to be important for wool and meat today and are also occasionally raised for pelts, as dairy animals, or as model organisms for science. Sheep husbandry is practiced throughout the majority of the inhabited world and has been fundamental to many civilizations. In the modern era, Australia, New Zealand, the southern and central South American nations, and the British Isles are most closely associated with sheep production.