Warcraft III takes place on a map of varying size, such as large plains and fields, with terrain features like rivers, mountains, seas, or cliffs. The map is initially hidden from the player and only becomes visible through exploration. Areas no longer in sight range of an allied unit or building are covered with the fog of war, meaning that while the terrain remains visible, changes such as enemy troop movements and building construction are not. During a game, players must establish settlements to gain resources, defend against other players, and train units to explore the map and attack computer controlled foes. There are three main resources that are managed in Warcraft III: gold, lumber, and food. The first two are required to construct units and buildings, while food restricts the maximum number of units the player may control at one time. Additionally, producing units over certain amounts will decrease the amount of gold one can earn, forcing players to focus on playing with a limited number of units.