Barley is an annual cereal grain, which serves as a major animal feed crop, with smaller amounts used for malting and in health food.

It is a member of the grass family Poaceae. In 2005, barley ranked fourth in quantity produced and in area of cultivation of cereal crops in the world (560,000 km²)[1]. (H. vulgare) is descended from wild barley (Hordeum spontaneum). Both forms are diploid (2n=14 chromosomes). As wild barley is interfertile with domesticated barley, the two forms are often treated as one species, Hordeum vulgare, divided into subspecies spontaneum (wild) and subspecies vulgare (domesticated).

The main difference between the two forms is the brittle rachis of the former, which enables seed dispersal in the wild. The earliest finds of wild barley come from Epi-Paleolithic sites in the Levant, beginning in the Natufian. The earliest domesticated barley occurs at Aceramic Neolithic sites in the Near East such as the (PPN B) layers of Tell Abu Hureyra in Syria. Barley was one of the first crops domesticated in the Near East, at the same time as einkorn and emmer wheat.