Hay is a stored forage that is essentially characterized by having low moisture content(less than 15 %). This means it can be stored unharmed by fermentation and moulds. Although most forages can be stored as haylages it nutritional value of later is related to the type of plant used.

Hay making is the most common and easy method of preserving seasonal excess of green fodder and the only method of preserving farm by-products. The principle involved in hay making is to reduce the water content of the herbage so that it can safely be stored in mass without undergoing fermentation or becoming mouldy. Legume hay, non-legume hay and mixed hay are the major three types of common hays used in livestock feeding.