Book excerpt: Opuntias are multipurpose plants that are increasingly being used in agricultural systems in arid and semi-arid areas. Due to its high water-use efficiency, it is particularly useful as forage in times of drought and in areas where few other crops can grow, and it is now considered a key component for the productivity and sustainability of these regions. This publication presents current scientific and practical information on the use of the cactus Opuntia as forage for livestock.