Reindeer pastoralists have, for centuries, followed free-roaming animals throughout the Eurasian Arctic. The closing of national borders about a century ago forced the reindeer pastoralists to adapt to new conditions. Today, environmental conditions are changing rapidly with climate and land use change. Local history, migration and pasture use strategies of reindeer herding, and also the biogeography of grazing grounds during summer and winter, differ considerably between the countries. These differences also affect interactions with other forms of land use. Coexistence between reindeer husbandry and other interests requires an understanding of the differing preconditions in the natural environment. The main scope of this chapter is reindeer forage selection and adaptation to the arctic environment, as well as the use of pastures by reindeer and for reindeer husbandry and what affects their use during different seasons.