Barley or Common Barley (Hordeum vulgare) is a species of annual grass in the Poaceae (or Gramineae) family of true grasses. It has a self-supporting growth form. It is associated with freshwater habitat. Common Barley has simple, broad leaves and yellow flowers. Barley is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Its grains are often used as food or to make beer and other malted drinks. It is also used as a cover crop in wine-growing.

As a cover crop barley is neither expensive or hard to find. Barley is easy to grow and sow. It can grow quickly into a thick green carpet, producing more biomass than any other cereal crop, suppressing weeds. It also has very good erosion control.